The only things that need to be under a mobile home are two long concrete slabs---is that what you are calling a footer?

The slabs here in Kansas are 4" thick, built like a driveway would be built(ok, two very narrow parallel driveways).

There may be totally different regulations in Indiana. Ask the city/county codes office for the necessary info.

Cashing in any stock to throw good money after bad on a "home" that depreciates as soon as it rolls off the lot is just about the worst idea ever. No bank will lend on an older mobile home regardless if it has footings or not, despite the "information" provided by the self interested relative that's trying to snooker you here.

The entire value of that property is in the land only. If you can afford to buy it cash outright and live in it while you construct a conventional home on it, that's the only way it would ever make sense to purchase. If you cannot afford to do that under any new environmental regulations that exist to protect the lake, then pass this "opportunity" by.