It depends on what configuration the boat is whether or not a forklift can even get into the salon to lift the motor. With my sundeck there is absolutely no access for a forklift to get to the engine. To remove the engine there is a soft patch in the flybridge deck on the port side to take the engine out the top. However the lift has to be very tall to get to it and I would have to remove the hardtop which I won’t do. So I used a beam and moved the engine over to the other side. As to replacing the fuel tank, my back went out right after I pulled the engine. I had 9 procedures on it last year and have about given up on getting it fixed so I decided to not try to replace the fuel tank, mine isn’t leaking but I just wanted to replace it proactively. Instead I just cleaned up the engine room, painted, replaced wiring, replaced hoses, redid the bonding system, etc. i could not have done the work with the engine in place so it worked out ok after all. I took out one transducer and one through hull and glassed them closed. Also was able to replace the head in the aft cabin with a new Marine Elegance since I was able to get to the hoses.
As to repairing a fuel tank, why would you consider that. My new tank was going to be 210 gallons and cost about $2500. If I had the tank replaced by a marina it would cost about $10,000. Why would I spend 3/4 of the cost and still have an old tank that will leak somewhere else at some time in the future and then I pay another $7500 to remove and replace again??? That makes no sense at all, if you pull the tank out then put a new one in. Even if you do the work yourself you don’t want to be doing it a second, or third time. It is a lot of work. Besides a new tank will enhance the value of your boat, or at least make it much more attractive to buyers. Telling the buyers that you repaired a leaking tank would subtract value to me because I would be thinking about the next leak.