Is it acceptable, when composing in 4 parts, to let a measure pass in which a triad or perfect chord is not created by the voices? (two voices double the others..)

Sure, anything's possible. It may not sound good though, but the more experienced/advanced composer can make it work . . . I think.

You should look up those notes I gave you. They have some guidelines on the voice doublings.

Ok, will do. Was just trying to avoid making the bass play the only 3rd...