I rode it this summer, leading a group of soldiers along the route. We didn’t just do a straight line point to point but rather hit just about every trail centre along the way. PM me you email address and I’ll send you the GPX files if I can find them.
As for training, most of the guys hadn’t really ridden proper mtb routes before let alone done any training; therefore it is plenty achievable for someone of a decent level of fitness and a fair amount of determination and some experience on a bike.
As for tips…get some support is the main thing. Doing it with no-one to ride with at least or even better, to meet you at each stop with a warm van and a cup of tea makes things ten times harder. It’s not impossible though as we rode past guys divvying each night with absolutely no more support than the stuff they could carry on their backs.
Prepare to get wet and have plenty of changes of clothing (esp socks!) Oh, and food: eat lots.
DO IT!