since you have already covered the bare wood i wouldn't remove it especially since it might damage the Koverall that you want to keep. i checked a chemical compatibilty chart and you shouldn't have any problems with epoxy over nitrate dope. you will need to smooth out the Koverall area your going to cover as well as you can so that will make prepping the 'glass surface easier before you apply the tape if your going to do that.

you have a very nice model there. i would try these techniques on a scrap piece of wood (the same type as is on your actual model) complete with Koverall to make sure everything will work out as planned before you try it on the real thing. a couple of hours or evenings won't mean anything in the end.

as for masking tape, i use general purpose stuff. if it's real sticky i apply it to my workbench first to remove some of the tack before applying to a model.