I'm a "heavy-medium" armor wearer who rides a courser, total cost: 59,093 Max Upkeep: 4,132.
Nordic Warlord helmet (48 head armor)
Heraldic Mail with Surcoat (38 body/18 leg)
Wisby Gauntlets (5 body)
Mail Boots (35 leg)
Courser
Heavy Lance
Broad 1h battle axe
knightly heater shield
I usually get a fair share of good multipliers and I still manage to lose money consistently. Some gens with this build I've lost 40-50 thousand gold, some gens I've only lost 15-25k gold. And I'm using a cheaper horse than a 5 riding "heavy" horse, and not using "heavy" armor.
If you decide to go heavy cavalry, I'd suggest not getting more armor than I'm wearing. The heraldic mail looks ugly, but stat-wise is my favorite armor for cavalry (18 leg armor). Use good leg armor on horse, helmet is probably not even necessary unless you plan on being dismounted a lot. Also gloves are nice, but you don't need to wear expensive gloves, mail mittens (3 body armor) still help.
If you sell your loompoint (say for 700k) and buy a +1 item for 450k, that left over money SHOULD hopefully last you 2 or 3 generations and you will be able to keep looming the first item another 2 times to get a masterwork. I'd suggest looming either your weapon first (if infantry) or your horse first if cavalry.