I still haven't figured out how gold is going to get into Strategus. If it is straight from cRPG then the powergrinder heirloom masters with their millions of hoarded gold will make gold worthless or essentially run strategus. A self-contained strategus is best with options to allow money to transfer into cRPG (Giving a reason to play strategus even if it is to just farm/mine and not participate in any battles), of course in this instance upkeep on items would have to be increased dramatically.
It seems to me there are two options here.
Option A: Full Communism - ("The game Pharaoh")
Abolish the idea of any monetary currency in Calradia, pretend they have never invented anything economically beyond Trade and Barter. Gold doesn't exist and no machines exist for minting. Instead the currency is food.
How this would work in game:
Fiefs could grow different foods and the fief owner could determine how much each farmer gets to keep for himself. Fiefs could make food/ mine for resources/ breed horses. The government takes food taxed from farmers and uses it to purchase the resources/horses off the miners/etc. the government then takes these resources to the town, along with the taxed food. Fiefs would have a limit on total population, this stems from the fact that the more houses you have, the less space you have to farm, and the further away from the village you have to go to hunt/farm.
Towns would take the resources, pay the artisans in food, with more food going to better "Smiths", and base wages for the production line. Saddles could be made in towns and horses either devoted for caravans, or sent to castle to be trained for war. Trade caravans would originate and conduct business in towns as hubs of food, equipment, and raw resources.
Castles could receive leftover food from the towns or straight from the fiefs themselves in order to train troops and feed the armies/pay for generals. People could work in the castles as drill instructors or horse trainers. Castles could also be used to store food and keep it safe from raiders/enemy invasion. Castles would provide the lowest rate of consumption for garrisoned troops, due to occupying less land than a town, stricter rationing, and having no penalties to nearby fiefs for foraging. Wars would still require troops mustered from across the land to form armies of significant size however.
Any food leftover at this point could either be used to trade or maintain a "Strategic Reserve" in castles or towns (or even fiefs but they are not very protected and prone to raids) in case you suddenly lose a number of your fiefs in the opening assaults or surprise attacks. I say maintain because food will spoil over time, preventing hoarding of food and the increase the desire to trade it or convert it into troops, because a number of your troops will retire when they get too old.
In addition, larger armies in a single area would consume more food, as there would be less to forage. A small band of 10 men might simply be able to live off the wilderness, while armies of 1000's would depopulate the local fauna and hurt production in nearby fiefs. Armies garrisoned in castles/towns would consume less, but not fiefs for the previous reason. Fighting a defensive war would be very harmful and prone to greater attrition. But attacking armies would suffer too due to food being expended to maintain supply lines if the invading armies were coming from a great distance and such.
Pros:
Food Spoilage/Old Soldiers/Foraging provide great opportunity for tweaks in order to balance gameplay.
Raider or bandit clans could raid fiefs and caravans while leaving castles and towns immune. Thus giving purpose to have your armies out on patrol or bribe bandits.
Cons:
Food doesn't translate into cRPG very well, a system for players to "eat" their food in exchange for cRPG gold could be put in place.
Mercenaries historically didn't fight for "food", so players would receive the food planned for the troop salaries (so in essence troop tickets would only consume in the field and for initial training), and rather than be official "mercenaries" simply take the role of a faction's loyal soldiers. Players who both produced goods and fought in battles would naturally receive more food than those who just did one or the other, as a family could still work while the sons/husbands are off at war.
Option B:
Gold and machines for minting exist, commerce thrives as currency does not expire, caravans are faster and can carry more wealth/value than barter caravans. Laissez-faire and the free market forever.
How this would work in game:
Similar to the above, replace all instances of food with money. Except for a few differences, fiefs could produce precious metals which could be sent to the capital city for minting, this would detract from their ability to produce food/equipment. All fiefs would have this ability in order to have a single currency amongst all factions, but some fiefs might have this resource be more plentiful than others and produce more per worker. The capital city would be responsible for making the currency and then distributing the coinage throughout the land to pay for everything.
Pros:
Money is money, and could easily be converted into crpg gold.
Food would still be important for war, but not for production. (Maybe this is a con to some?)
Cons:
Has a heavy emphasis on protecting your capital (maybe this is a pro?), losing your capital would shut down your empire for weeks.
Money doesn't spoil, hoarding would become prevalent especially amongst the merchant empires that won't war with anyone. Tweaking would be more difficult and I forsee more possible rollbacks or stagnation as the game goes on and some empires simply have enough gold stockpiled to have massive armies.
Inflation of the currency means the conversion factor to cRPG would have to be closely watched.
Raiders would be limited to cherry picking around the capital and trade routes between factions.
TL; DR I love words and 'sperging out, don't mind me, you could safely ignore this and have a much better day, this is just practice for when I go back to university and have to write lots of bullshit to increase the page count. This didn't seem like so many words on my 1920x1080 screen. Also I am high as fuck.