You can't really solve this by altering the wing' geometry, though some engine upthrust may ameliorate the tendency.

The reason that you can't solve this is that it is not a "problem" ... it's merely a trait of that airframe layout. That is, it's perfectly normal. Some full-sized aircraft, with high-mounted engines, behave in the same way. They pitch down with power.




So, you can try some engine upthrust ... try 5 degrees or so.

You can mix in some elevator trim with throttle, such that increased power coincides with a little "up" trim.

You can just get used to re-trimming for each power setting.