Transponder antenna - blade vs stub monopole

In article brianDG303 writes:
Is there a downside to mounting on a ground plane inside the fuselage
of a non-carbon glass glider?

Since the ground plane should extend at least 23 inches in each
direction around the antenna, it is probably hard to get that inside
the glider.

One that extends front and back but is more limited to the sides
(perhaps wrapping around inside) probably would work, but would be
a bit reduced from a full ground plane.

Alan