You have the idea.
Orcs get Berserker, which is 20% extra earth and fire damage, +10 physics and +5 speed and unlocks advanced combat skills. Pair that with Earth Shatter and Fire Cleave and a pair of orcs can kill most foes in Bandit Forts (including non-buffed Assassins) before they ever get a chance to counterattack.
(Dragonkin and Valkyries are also OP and can be substituted in with only minor changes to overall gameplay.)
I'm wondering if a hybrid strategy would be best. Start off with two orcs to farm Bandit Forts starting around day 6 and have them powerlevel your other characters, including the prostitutes.