> Hitec does not recommend their 555, micro, receiver for fuel use <

No HiTec advertisement for all the years this receiver was in production ever limited the 555 to non-wet power use. And the HiTec service department never cautioned me about this. Perhaps you have some other model receiver in mind like the Feather? And come think of it, HiTec never had any objection to using the earlier 535 receivers with piston engines, either.