If you haven't already bought the Cobra and don't want to do a permanent install, you could also look at something like the
Midland 75-822. That is a "hybrid" HT/mobile CB. Basically it is the top portion of a handheld CB and then the bottom portion is either the battery box (in which case you have to use the "rubber duck" antenna) or you can replace the bottom portion with an adapter that has both a 12v power plug and a female PL-259 socket for an external antenna. Like the Cobra, the Midland includes 7 (or is it 10?) WX channels as well as the 40 CB channels.
I've been using the Midland for years and it works fine for trail use. No permanent install means it comes out after the trail run (and I use a mag-mount antenna on the center of the roof.) The handset has a clip on the back, and I just run a long loop of 550 cord and hang it from the mirror when I'm on the road. When on the trail the mike normally sits in my lap.
Here's a photo of my cockpit, you can see the Midland hanging from the mirror on the left side of the picture:
There are probably better CBs out there but for the price (under $100) and the ease of install, this one is fine for me. On trails it seems to work as well as any other inexpensive CB using a mag-mount antenna.
I've never used it as an HT (it actually comes with two battery boxes - one for rechargeable AA batteries and one for alkalines. The charger is also included.) My guess is that with the "rubber duck" at 27Mhz, it would fall into the 'better than nothing' category.
Now that I have my 2m mobile installed and a dual band HT available to use, the CB will most likely be 'backup' but since (so far) all the people I off-road with use CB exclusively, it will remain in my vehicle on runs for the foreseeable future.