Hey NOT..
The radio is designed to be mounted flat. The design most likely has consideration for heat dissipation. The radio will produce more heat while transmitting than receiving. Mounting it in any position probably won’t be an issue as long as there is sufficient air space around it.
Regarding the noise. I spent many hours trying to eliminate EMI and spark noise from my engine on my 1985 standard cab. I ran a 10 gauge wire from the frame to the bed to make sure it was ground because my antenna was mounted in the bed right behind the backglass slider.
I ran CB coax from the radio to the battery. I split the metal shielding and connected that to my ground directly to the battery terminal. I connected the stranded center wire to the positive terminal on the battery. That eliminated a lot of noise. I also installed a cheap Radio Shack band pass filter on the ground lead at the radio. If I were to do it again, I’d buy this:
https://radioworld.ca/wor-nf20Regarding water proofing, I don’t think you can get it water proofed enough with anything like a sealer. If I had to kluge one together I’d look at something like a water proof electrical box, then drill a tight fitting hole for the mike cord, and silicone it. The mike would have to be mounted high up and maybe wrapped in a plastic baggy.
https://www.homedepot.com/p/Carlon-4-in-x-4-in-x-2-in-PVC-Junction-Box-E989NNJ-CAR/100404097They come in different sizes.
If I were really concerned about using my CB and possibly getting it wet, I’d buy one of these:
https://www.superwarehouse.com/Uniden_Solara_D_UM380BK_-_Class_D_DSC_Marine_Radio/UM380BK/p/2129285?gclid=EAIaIQobChMIyqv776Ki4AIVlMVkCh1N8AqkEAQYAiABEgKYrvD_BwEThat’s just my opinion – it may be worthless.
Gnarls.
