When the 300TDi's had the early belt failures, the maintenance frequency on the cambelts were reduced to 60 000km (about 35 000 miles). I replace the belt in my Disco every 80 000km (50 000 miles), and every time I remove a brand new belt, so the 100 000 mark is definately do-able in our high dust climate
I do have a crank-locking tool which I use for removing the crank bolt
Incidentally, how do you torque that bolt the last 90 degrees ? I stick a piece of paper, marked with the appropriate 90 degree marks on it to the crank pulley. But, due to the lack of space, lining up the marks from above is difficult