D'oh, I'm an idiot. I never had to worry about blocking RF with my previous composite projects, and I just realized that Carbon Fiber (CF) makes a pretty good RF shield. I was planning on reinforcing the leading edge of the wings and the belly of my ZII with CF, but now I'm concerned that I could have RF issues if the coverage is too great.
I would assume that since my RC Rx and Video Tx are on the wingtips, as long as the CF isn't near those areas I should be okay (nothing near or below the antennas). Or, I'll switch to E-glass or Kevlar/Aramrid.