Antenna under fabric in welded tube ship?

I would like to put internal nav and comm antennas in a series 5
kitfox, which has a welded tube frame. Could reasonable performance
be obtain with elements on the inside surface of the fabric, but out
side the frame? Seems to me this is essentially mounting the antenna
very close to a so-so ground plane. How much loss and alteration of
the radiation pattern is likely? Would the situation improve by
minimzing runs parallel to the frame tubes?

Thanks!

Jon