I'd look at mounting it vertically on the side of the ROPS on the side opposite the side I most often mount and dismount. Many CB radios have the speaker on the bottom. This mounting arrangement aims the speaker at you.
I have a VHF radio in all my farm vehicles (not CB) and the tractor has the radio mounted vertically to a cab structural member just to my left but out of the way for ingress and egress. Then comes the question of hot all the time or just when the key is on. I prefer the key on approach so you can't forget the radio is on and run the tractor battery down over a few days of non use. I have the mike holder attached to the side of the radio mount. This mike location works for me as I don't talk much on this radio. If I used it a lot I would use aircraft style headphones with a noise cancelling boom mike for hands free operation.
CB is OK and works but would not be my first choice. You can buy a Baofeng hand held VHF/UHF radio programmable for FRS and GMRS (or other radio services) on Amazon.com as well as many other suppliers for under $50 They are FM (static free) and no truckers and bozos jamming the channels. They use rechargeable internal battery but you can get an inexpensive accessory to let you power them from a cigarette lighter (or 12 volt dc source.) They have built in mike but can use accessory external mike on a coil cord (handy if you mount the radio to say the ROPS using its supplied pocket clip. They will work fine with a set of ear phones with boom mike. They will cover all the NOAA weather channels and even play FM broadcast stations. If you program them for FMRS channels then no lisc is required. I use mine on the ham bands as well as marine band, NOAA weather, and FMRS. They are interoperable with the FMRS handhelds sold at Wally World.
Patrick AF5CK