I personally can't see any reason why stacking clen and lipo6 would be a problem; at least from a potency standpoint. 80 mcg is widely accepted as the lowest effective dose for clen and when you consider how some others stack clen with T3 at much higher doses (with androgens of course), stacking clen with lipo6 like you described doesn't sound that intimidating.
Perhaps someone else with some indepth knowledge on how yohimbe works could offer you an insight into any synergistic action you could expect. Personally I believe sesathin and clen would make a better combination because sesathin appears to be quite effective at liberating fat stores and promoting the burning of fatty acids which would work in good combination with clen's calorie burning potential.