I'd put the 2/70 on the fender and the others on the roof.
10" if possible will be good seperation. the frequency separation will make them blind to each other.
You do realize that 5o+ watt antennas have been mounted that way for decades with no ill effects? anything above the Gigahertz level will be fine, as long as you are nt touching the radiating element.
LOS is a missleading term in this case. Unless you put the antenna right up agaist the body...
For chatter on the trails, this is all you need. Add a good antenna, tune it with a external meter and be happy. https://www.rightchannelradios.com/products/uniden-bearcat-pro-510xl-cb-radio
Should you go The Amature route Go Kenwood or Yaesu.
GMRS ? I guess the Midland is ok, but remeber you...
Too True, But will allow you to find part numbers alot easier than the company websites in many cases.
https://www.ebay.com/usr/antenna2-waydirect
https://www.ebay.com/usr/texxcomm
I've had good luck with these 2. especially finding new old stock in or close to the bands I want, just a...