go for it, i drove my Ford GTB to Houffalize in the Ardennes for the BMVT winter rally, it was an 800 mile round trip. It was a great trip even though it was extremely cold (-19C). We took the scenic route on the way there from Le Havre, took 11 hours of driving to get there! on the way back we used motorways and it only took 7 hours , Averaged 10 MPG! lots of very long steep hills to climb, down to 2nd gear a few times on main roads!
My advice would be to put some really good lights on your truck, including some decent flashing lights (i used flashing LED warning lights on the rear). My GTB is 12 volts with an alternator so i have a split charging system set up as a back up power source and for running sat nav, charging phones etc. As for spares i carried a head gasket, water pump, complete distributor,spark plugs, fuel pump repair kit, some spare HT lead and some wire. Also grease, gear oil, engine oil, brake fluid and antifreeze. Thankfully i did not need any spares.
It is certainly a challenge taking truck on long road runs, particularly on your own, going with a group of vehicles is a far better idea but not always possible of course. I had a few contacts in the Belgium MVT who i got in touch with before we left and they offered to help if we any assistance enroute which was vey nice of them. We were hoping to win the "furthest travelled" prize at the rally but we soundly beaten by a guy from Austria in a Chevy 1.5t and another guy from North Denmark in a Dodge.
Most importantly enjoy the challenge.