When I drove my Deuce back from Kentucky, it took me $130 for a plane ticket, $50 donation to the VERY nice SS member who gave me a ride and helped with the recovery, $300 in fuel (not counting the half a tank of WMO I started with, thanks to friend's donations), $40 in tolls, plus food. I averaged 10 mpg. Total cost was around $550-$600 for the 1100 mile recovery. I didn't just do it to save money, I also wanted the experience and the trip. It could have easily cost a lot more if i had even the slightest problem. Now double the fuel cost for the 5-ton, and its up to $900...getting close to what a shipper would charge.
But you said you are doing this for the fun. I had to do my trip with a truck i didn't know, but was in excellent condition. Even so I spent most of a day doing the PM. The others had excellent suggestions re: tools, parts, etc. If you carry everything, you either won't have any problem, or else it will be a major catastrophe that will really end the trip. I'll hope for no problem.
Besides the smaller Pm stuff (fluids, filters, etc.) I would pull all hubs and check seals, grease bearings, and check brakes. Take time to check every wire and hose, and follow them all. From what I've seen, our trucks are notorious for having a wire or hose rub somewhere, and a long trip causes it to rub through. Secure what you can, and use a layer of larger rubber hose to protect what you can't secure.
And last- choose your route early, and ask for contact from any SS member along the way who would be willing to help. Keep a little database with their name, contact info, vehicle(s) they own, and limit of help they can, or are willing, to offer. Trust me, if something goes wrong, you'll want to quickly know that Bob who lives 20 miles away only has an M37 and no garage, but Ken has a crane truck, full shop, and spare parts, but is 50 miles further.
Jim