I have a "slow" combat that is cut from white foam it does have spar on the top and bottom cut into in I think it is 1/4 inch by 1/8th full length with a mono-cote type covering thats it. Full lenght is 42 inches and I use rubber bands to keep it on the plane. I have never had a problem either have the 10 guys that I fly against. I run a .15 os on it so no it's not going fast but. You said that it is a beater type plane I think you would be ok with just full length spars and no glass or balsa sheeting, let us know how it works.