Hi,
I have a 86" QQ Yak and run 4x5985MG and 1 5955TG directly to a Futaba R-149DP with no issues, i think in a 50cc airplane Powerboxes are oversized.
In my upcoming DA85, 36% Ultimate, i will not use a powerbox either, i will use two Futaba recievers and a powerbox gemini. The reason is mostly the weight in general and about the weight behind the CG because of the DA85.
Here is a 3D CAD drawing how i setup the powersystem:
