Sailplanes have been flying for years now with flaps and all they do is mix in some elevator trim compensation to allow for the nose up pitching action from the sudden extra lift. Models with lower aspect ratios and shorter tail moments often see the opposite effect and find they end up with a nose down pitching reaction due to the increase in pitching moment being more effective than the extra lift. But here again some elevator mixed in will compensate.

I say do nothing. Just put it where you eyes like it and where it's convienient to hook up the controls. Stick to the usual wing and tail incidence angles for the type of model. Mix in some elevator later on if needed. It'll be fine.