The electric tail rotor is interesting - but the above suggestion of 30-40Kva power generation requirement, and a 30Kva electric motor requirement, is not realistic.
I'd suggest perhaps 3-4Kva power generation requirement, and 2-3Kw electric motor would be quite adequate for a rotary aircraft of this size and weight.
Both of which are quite feasible, and coupled with a capable lightweight battery, would provide all the power and backup needed.