IMO If your going to go less than 1/4 scale and clip the wing she is going to be fast, land fast and do everything a fast plane will do.
But if you build super light the 1/5 clipped wing will be docile, It has to be light! Go with light gear!
I built the Goldberg in the clipped and the Sig 1/4 scale clipped. the 1/4 seems to have enough mass to carry the load even with its shorter wing.
One could get by with a smaller 4 stroke, Saito 56 or maybe LA 46 if you clip the wing on the 1/5. It all depends on what your end goals are. Mine were built to not fly scale !
The OS 70 is a little heavy for the power.

DJB