Mmmmm..... programmed in "downthrust" er.... you know that's what we call "CHEATING" don't you?

While this trick would work for power on to power off it could backfire on you if you don't know the side effects. For example suppose you go into a full throttle dive and for some reason want to reduce to idle while in the dive. The sudden shift in elevator trim will make the nose want to rise sharply instead of maintaining the dive. Similarly if you're floating along nose high and stuff the throttle to full the initial tendency will be to dive a little until the speed rises enough.

I'd still suggest sneaking up on a best pitch stability CG for each model and pilot and then fudge in some mixing at the Tx if you want more.