My efforts
This type of project was a fascination of mine some time back. I looked into many options including
various mini-pc boxes that could be trunk mounted on radio rack etc, like intel NUC.
I originally tried a refurb toshiba windows tablet I got for not much more than 100 bucks. It had sufficient horsepower to run unitrunker and decode p25 with dsd. Problem was Toshiba kept limiting the functionality of the one USB port to stop you from sending/receiving data and charging. After alot of work and research, best I could do was almost maintain battery (with a special cable) then get data out by having to use a powered usb hub, to which I connected
the rtl dongles. The result is functional, and I run it on my desk sometimes, but resulted in a rats nest of wires.
Next, I found a cheap windows netbook on ebay for 100 bucks. Much easier solution. I got two 5 dollar LTE antennas which do great on 700/800 and they stick up off the screen like rabbit ears. The netbook has full sized usb ports, so I attatch the dongles with short cable extenders so as not to stress the usb ports on the netbook. This setup has worked reasonably well, and I use it mobile on trips if wife is driving. If you wanted less clutter I suppose you could do something like sticking the dongles and cables to the lid of the netbook with epoxy, or having some type of remote hub and antennas in your trunk, with just a usb exentension cable to the netbook.
FYI forgot to mention both of these setups have been used to run, I believe what is called rtl-scanner, that does spectrum sweeping.
I would close with this. I think ultimately a windtel tablet offers a pretty simple and elegant solution, given the built in touch screen, provided you
find one that can send/receive usb data and maintain a charge/keep powered up indefinately.
Good Luck and let us know what you decide; happy experimenting!
KB5UDF->W5JAB