Cactus has the line on Insurance. He works outta TX, but I think his agent will cover other states as well. Here's the link:
http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=102830;hl=He said she saved him a bunch of money. Worth a look at least. She specializes in rig welders.
You got a nice truck & bed. Waterjet on the diamond plate? I would look into what was mentioned about a pallet system, so the bed of your truck could be used for many different things. A pin lock system would do fine. You could chain it too & keep your bottles & welder on it. I'm not a fan of propane, but you could mount a couple tanks on it & use straps to hold them in place. This is what I did on my trailer. I added the bottle racks after the fact, so I had to work with what I had.
I would consider a bigger diesel powered machine in the future, if you want to do structural gigs & CAC on a regular basis. The 300 amp machines just don't cut it for that.
Here's a pic of how I set my little trailer up. It's nothing special & some think because they own big contract companies, that you need every tool under the sun to work. A good welder, torches, a GOOD vise & some grinders & hand tools will do 99% of any structural you will ever encounter. A 20+ CFM gas powered air compressor is a really nice tool to have as well.
Good luck!! Steve.