holding tank replacement

Hello All - I have a 1978 32-2 originally equipped with an ElectroSan which 1)which can not be used in my coastal cruising area and 2) which was also quite dead when I purchased the boat so immediately removed it and resorted to a porta-potti. I intend to replace it with a holding tank and it...

Has anyone pulled out the holding tank? Any lessons learned, or tips? It looks like a bitch of a project because of its location (forward area of the cockpit locker), and the amount of dismantling that what seems to be required.