It will need manoeuvring (side to side, funny angles) to get the pick-up pipe and float through the hole, but it went in that way so it is possible. Use a torch to see what's in the way, or look at a supplier like Der Franzose for what the unit looks like.
Be very careful with fuel tanks. The cutting you suggest (and the welding presumably required later) will make them explode, often in a fatal manner.