Mount a wireless receiver in a profiler head

I'm looking to make the most compact solution possible with a minimum of cables to connect. So far I've had my profiler head mounted in a 6U effects-rack with a Line6 G90 wireless receiver for my guitars. There are of course much more compact wireless receivers on the market so I wonder if there is a receiver that would fit in the cavity at the back of the profiler (fixed with screws). The unit would have to have an external antenna to pull out to avoid problems with the profiler's cabinet shielding the signal. It would also be nice to be able to feed power to the unit directly from within the profiler. The output from the wireless receiver would be soldered in parallel to the front input on the profiler (the secondary input is way too noisy). This would provide the same functionality that I currently have, but lighter and it will fit in my KPA bag if there are no protruding parts.

Any recommendations?

[Maybe an integrated DC power-supply and mounting-brackets for extras could be useful additions to the wishlist for future profiler designs.]

Quote from Ingolf

Even the small Line 6 G30 that I use (which doesn't need an antenna at all) doesn't fit in the cavity properly.

The problem with putting a receiver without an antenna in the cavity at the back of a KPA-head is that the metal cabinet will block much of the direct signal and you are left to rely on much weaker secondary signals bouncing off walls an whatnot.

I may eventually do a custom job and mount the guts of my G90 receiver inside the KPA head. Antenna-BNCs would mount in the upper corners of the front panel, and there would be holes cut in the KPAs top for the G90s buttons and LCDs. This would of course void any warranty on both devices.