A stock Battle Floyd uses a full-thickness hard balsa spar. It works ok for flying against other Floyds, but it IS prone to breaking. I started flying combat with Floyds.

I suggest you get some 1/8" fiberglass rods, and cut a slot top and bottom and put them in the wing. If you can stand to loose 1/4" of wing chord, then just leave the wood spar out.

With either spar, I suggest you NOT cover the entire wing with the bi-di tape. That stuff is HEAVY. I just use a strip over the top and bottom of the spar, another strip along the TE, and one on the LE. If you do it right, the strip around the LE will reach the spar strips, or be really close. But you don't need the heavy bi-di between the spar and TE.

Then I use the colored tape over the whole wing of course. I think the colored tape is actually stronger than the heat-shrink coverings because the overlaps in the tape acts to stop cuts and tears from spreading. And the tape does shrink a bit with heat to take out wrinkles.

Btw, another quick tip with the Battle Floyd. Don't use wood on the fuse sides, you get a much strong fuse if you use 4mm coro instead. And if you taper the back of the fuse, you really knock down the drag and weight for an easy performance boost. If you look at http://www.midatlanticcombat.com/rapier.htm you can see what I've done with a Floyd-inspired fuse that I redesigned. You can take a lot of the ideas there and use them on your floyd kit.