Clean:

Your wish for free flight might be a little compromised, granted, by rudder control, or worse, by rudder AND elevator. And then tie motor control in too...

But a boosted glider is a nice compromise. I have a Goldberg "Electra," an easy build, andusing a geared motos it has good power endurance, once at altitude just shut the motor down, the prop folds, it's thermal time. And you don't need a DT.

Bill.