Antennae

I have a new glider on order and naturally I want to build-in all the
things it will need over the next ten years at least, rather than adding
things later piecemeal. In the non-carbon part of the fin I plan to have a
radio aerial, a transponder aerial and a Flarm aerial. However it seems
that ADS-B (In & Out) is the coming thing and so presumably another
built-in aerial would be a good idea, rather than something above the
instrument panel. Have anyone fitted four aerials in the fin and do they
co-exist happily with each other? I don't know if differences between
European standards and US standards would make a difference to the type of
aerial fitted.