Howdy from Kansas! Couple ideas to skin this cat, UpDown hit on the main items I was going to suggest. Pre-wire power and stow a magnetic antenna under a seat. Snag a mobile with a remote-control-head, stow the head in the glovebox when not in use, cable under the seat or, pre-wire the head to wherever it'll be used and leave a little pig-tail of wire.
For mounting either velcro or a magnetic mount would be feasible. I've recently started using my FTM400 heads with a magnetic phone mount.
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Another option if you want to maintain more portability and not go with a mobile, pre-configure the vehicle for use with a portable. Find a solid portable option and snag a battery eliminator, SMA to BNC adapter (quick antenna connection/disconnect) and slap a magnetic phone mount on the back of the battery eliminator. The FT2 pictured accepts 13.8 in the side of the radio and just runs off that when turned on or charges the battery, I use it with a USB adapter on my F800GS. I keep a quick BNC whip antenna for portable use and can interface with a magnetic antenna for mobile use rather easily. Assuming power output isn't a huge concern and 5W will get the job done for you, this might be a solid option. Tons of other mounts exist such as this portable mount I use on the F800 from RAM.
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Hope that helps the wheels turn a bit for some ideas!