I would put 3 coats of dope (either, I always use Butyrate) thinned 50%, lightly sand each coat with 360 or 400, cover it with light or medium silk-span, 3 coats of dope, lightly sand each coat, then spray primer. I know its a trainer, but practice your finishing techniques on it. As small as it is there is not much area to sand. Have fun!
Don