I've dabbled in a few When World's Collide (Basically a crossover RP, though OC's from the many IP's & Franchises are involved, unless an event is on) RP Servers (Many of which have sadly closed their doors) in the past, so maybe something like this could work, but with NutScript involved?
PAC3 would obviously be needed, to minimize the amount of addon's being used. Just the textures & such for the PAC's would be required.
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Though, in all fairness, a Medieval RP server would be an interesting server to play on. However, you'd have to take various factors into account (What it will run on [DarkRP, NutScript etc....], what add-ons to use, what jobs to have, what map(s) to use etc...)