I completed the task of the oil pump bolt yesterday, and can confirm the sump did come out after just removing one side of the track rod end and moving the steering bar to one side, so saved removing the cross member. My bolt was not loose, but certainly not very tight and had no thread lock of any kind showing. Mine has covered 98K now, and has a full Land Rover service history! I used the original bolt, replaced with thread lock and left overnight before refilling with oil.
Replacing the sump was tricky, trying to keep the new gasket in place! A little tip is to put the long bolts at the back of the sump in first, before the shorter ones, as when I refitted the sump, all but one of the bolts went in, and the one that wouldn't grip was a long bolt at the rear of the engine, which meant removing all the shorter bolts to wiggle the sump into position, before the long bolt would take! Lots of time faffing! However, that could just be mine!
This is the sort of job that could take 2-4 hours, but if you get a few niggles as I did, you should allow a day to be sure!
Glad it's all done, a bit more peace of mind!