The problem with lances is that you really need to be 1-shotting people for them to be worth taking over, say, jarids or hvy axes. unfortunately to do that you need 8+ PT. with 8 PT you either have to put little/ no wpf in other proficiency OR wear peasant gear.
As such, I would strongly reccomend you get a shield and go for 24/12 with 8 Ps/PT with 4 shield, ath and Wm. you might be able to wear some light armor, but you'll have to figure it out on the wpf split. Even with 8 PT you will rarely 1-shot anybody with medium or higher armor, and with only 4 lances and slow movement you will go down rly fast and get frustrated at your lack of effectiveness.
As far as I can figure out, the only really effective way to make throwing work is to take a shield and 9 axes and play as a 1-hander with ranged capabilities. I really don't rate naked pure throwers with 16 spears. They may be fun to mess about with for a bit but I just can't see them being a viable playstyle as a main. too situational, too restricted by the ridiculous PT/Wpf requirement.