I don't see why not! Computer radios have only been available for what a decade? It definitely is easier to have computer radio to fly multiple airplanes BUT it's not necessary. As raideron mentioned, just adjust the airplane so that your trims are a neutral.

So, after you fly your plane, remember where all the surfaces are and adjust the clevises so that when your radio trims are all at zero, the plane surfaces are deflected as they were when they were trimmed. Then you could fly multiple planes.

Word of caution. The only thing you can't do is reverse the servos so be careful. If any of your servos are reversed, you'll have to remember to flip the switch or else you'll be picking up sticks!