Wow. Thats a HONKER of a hole. I'm going to pull the pump this wknd on my red car and I'll consider cutting an access hole for the future.
From what I recall before, lowering the tank was not hard at all. I dont recall having to do anything with the exhaust the last time. If the whole job takes me more than 1 hour, I'd be surprised.
You have to drop the exhaust as the tank sits above the exhaust pipes.