AC5ME,
Sorry, I can't help with the actual conversion, but you seem to be on-track. I send best wishes. I have some input that you may want to consider.
For the flight testing, I am hoping that you can tow up in the usual sailplane manner, and then conduct your performance testing while airborne, with no need to test the self-launching aspect on a do-or-die basis at first.
Assuming you are familiar with "Ground Effect," I would suggest a very long runway for testing, maybe even with enough length to launch and land without turning, if necessary. Build up some excess airspeed in Ground Effect, before commencing the initial climb.
In case your prop-stopper does not work as expected, you may want the ability to lower the motor and prop almost down to the fuselage, and have it held there. This trick may allow the prop-stopper to operate as it should, if it did not do the job with the power pole upright. A mechanical prop-stopper (made from flexible plastic) may do the job for you, if needed, but use that option only if all else fails. Once the prop is stopped, you can lower the motor and prop completely.
Seems like you will be making heavy demands on the batteries, on a continuing basis. I would want a sailplane parachute on my back as a matter of routine, but that's just me.
Interesting project. Best wishes. Please keep us posted.