Two Aircraft Design Ideas for CAS in Contested Airspace

The A-10 and Su-25 frogfoot are great planes but I have three competing designs somewhere in my mind 😀 which I wish this esteemed forum to weigh on. The basic parameters are:

1. Has to be single engined as part of a wider military-industrial plan.
2. Rugged, STOL platform
3. Low cost, cheap, easy to mass produce.
4. Has to run either on diesel or gasoline

Design 1:

Engine facing backwards (like typical UAVs) with a single aero diesel engine (for why diesel see: http://www.deltahawkengines.com/diesel00.shtml (scroll down to ch6 advantages of diesel engines))

Design 2:

Simple monoplane design, twin prop, single engine with a single aero diesel engine. The single diesel engine mounted between the wings will drive a propeller on each wing.

Benefit of D1 is simplicity and efficiency. Drawback, propellers at the back do not help wash air over wings, which limits STOL capability. Disadvantage of D2 is loss of power in the gearing of two props by a single engine.

Twin prop single engine becomes viable at all only because of the high torque of diesel engines.

Which of these would you choose?

Or would you be better of going with a slower version of the harrier setup? Can a Turbofan be made to run on diesel or gasoline? I don’t think gasoline or diesel could be used on a proper turbo fan engine (this is an absolute hard limit in this case).