Roadlover,
Does sound like battery connection issues however, we did have something similar happen to our '04.5 D/A when down in Florida a couple years ago. It lways ran great and I'd parked next to our 5th wheel in the CG after coming back from a restaurant. Next morning the engine would only turnover and occasionally sound like it was going to start with maybe one or two cylinders firing. That happened 3 times and then absolutely no firing at all.
Since it's a diesel which only needs compression and fuel to run and it was obvious that it had compression. That left a lack of fuel next. So, started looking at the fuel circuit lines etc and noticed a few drops of fresh diesel below the filter on the frame on engine's passenger side. Sure enough when I reached under the fuel filter, the bleeder screw was loose and the fliter must not have had fuel in it. I'd just had the filter changed before we left on the trip so it appears that the screw and jam nut wasn't tightened properly to begin with and over time loosed and then sucked air.
After tightening the bleeder screw and jam nut and then I pushed the primer plunger about 20 times (takes plenty of thumb pressure), I then tried to start the engine. No soap! So primed it about 20 more times and this time the engine instantly started and ran normal. Never had any problem since so that was obviously the problem!
It's worth a check! It cost's nothing!