Mounting "portable" avionics

Our club aircraft have GNS-430s and Strikefinders, but I'm looking at
adding some additional capacity. Long term, I suspect that ADS-B plus an
MFD is going to be the way to go. But ADS-B coverage is a little light
right now, so I'm reluctant to have members spending money today for such
limited capability. Yet I'm also reluctant to spend lots of money on
something to be replaced in the not too distant future.

One solution is to go with some portable device for WX etc. This has
additional advantages, like backup power and the like. And even though
we've standby vacuums, I'm also attracted to portables with some sort of
solid state AI backup.

The VistaNav and Cheetah 190 are high on my list.

But I'd like to have some type of "semi-permanent" mounting solution. It
should make the device tough to remove (although not impossible) and
should not be too annoying to the pilot not using the gear. I'm
especially interested in this to simplify the usual "wiring mess" which
portables with multiple add-ons impose.

What's possible?

Obviously, cost is a factor. So something that doesn't require a 337,
multiple inspections, a five-foot stack of paperwork, etc. would be
preferable.

Suggestions/recommendations?

Thanks...

Andrew
http://flyingclub.org/