I'm in Pa., so insurance is thrown on the trailer as soon as it is hooked to your insured vehicle. That covers anyone/thing that you may hit or damage with your trailer. That does not cover the trailer itself for damage, nor the items on the trailer.
I couldn't imagine not having my trailers, I find myself using it once a month at least for my Jeep, my tractor or lumber. Mine is a 25' car hauler with 2 x 6,000 Dexter axles and 4 brakes. I have it downgraded to 9,990 lbs gross (2,600 trailer weight) to save cost, going to 10K or above changes things here in PA pretty significantly. My father bought this thing new in 1999 and we have used ever since with minimal repairs. Tires are the biggest cost now days since I broke the rear axle tube hauling far above what should ever be on the thing. I had a road construction crew help me weld it on the side of a construction zone and then I got it home and sleeved it with schedule 40 pipe and welded it... but I did not have the 2 halves straight so now the rear axle is toed outward and cuts the tires. It's been like that for the last 10 years, not a big deal. Just monitor and replace a tire or 2 every summer. At least I never have rotted tires!
The dump is an Appalachian 7'x14' that me and my buddy split. I really don't overly love it being that it is to short. I'd like it to be a 20' minimum, but they just don't make that in a bumper pull dump. A tractor/loader/backhoe or any rear implement needs way more than the 14', and forget about bringing an extra implement wit you. With my 25' I can chain on to a 3-point implement and set it in the front, then have another on the tractor and drive on. 25' is cats patudy! I would never buy less than the 25' deck, if anything I'd go up to a 28' or 30'.