Arrrgh. When you don't have sufficient avionics, RP-1 allows pilot-input manual RCS fore and aft axis to still work (so you can fire an ullage-needing engine on a spin-stabalized probe), but RP-1 is suppressing kOS's set ship:control:fore to xxx. - only allowing actual manual keyboard or joystick input to fire RCS fore and aft. Mechjeb's annoying "RCS responds to throttle when main engines not active" is the supposed way around it but that's not right for using some other scripting system.

Thus I can't ullage my engine for ignition in my spin-stabalized first lunar orbit probe.

ship:control:fore is a get-only field that can't be set, and there is no ship:control:foretrim, and there is no ship:control:pilotfore to set.