Since your original query stated super slow I have to second the Butterfly idea. However I had one and a 25 size motor balanced better in that plane. Any 2 meter glider will fly fine with an .05 to .10 motor. .049 to .15 size engines can be placed on the nose or in a power pod that fastens on under the wing rubber bands. There is an endless number of possiblilties

Have fun.