I am wondering if I can get away with access from above (leaning into the rear access, rather than removing a side of the rear of the car).

When you are fiddling with bits of your car at meets etc, what are you fiddling with? What do you need to be able to access?

It seems to me that the fiddly bits are all on the top of the engine or around the axle.

Leaving the sides on will restrict access but if you can get to the engine mount bolts easily then just whip it out and start fiddling with it.

I hoped you might say that, cheers