there's a chance that the tech service dept of the company that made your freezer would confirm that there is no tubing or electricals in the floor of the freezer.
as for structural integrity, if OP cuts the floor through along the inside of the walls, as opposed to cutting the bottom off and taking the bottom inch of the walls with it, I think it should be strong enough to lift up with a pulley then reposition when lowered. you would use foam gasket on the perimeter of the bottom so when the freezer is lowered, it will compress the gasket and seal just the same way the top of the freezer now seals against the gasket which is on the top of the sides.
as for cutting the floor around the compressor area: I think I would invert the freezer and start cutting the bottom a distance in from the walls equal to the wall thickness plus probably an inch to be ultra safe. I would cut what was the front (when it was upright), the side opposite the compressor, then the rear up to a couple of inches from where the compressor is. then make the fourth cut, to remove the floor, giving wide berth to the compressor area.
next, I would turn it back upright and remove enough of the inside lining on what remains of the floor to see how much closer to the compressor you can cut the floor.
for a new floor, I think I would use 3/4" marine plywood or veneer plywood painted with a good quality epoxy paint. the marine plywood will be flat and true so the gasket material you use around the perimeter won't have any air gaps in it, and the epoxy paint will protect the plywood from the condensation that will accumulate.
I wish I could be there to help!!
Ken