We are planning on buying a new wheelchair accessible 2 section manufactured home and moving it onto farm property. Because the property has a high water table (about 5 feet from surface in extremely wet years), we can't dig a full basement. We would like to dig a shallow basement (crawlspace?) about 3-4 feet deep, so that the home can sit as low to the ground as possible. We would then grade the soil around the house, so we could use a slight ramp for entry, instead of a wheelchair lift. Does anyone have an idea on how we can supply access to the pipes, etc below? Would a bulk head work in one end, or could we cut a trap door in a closet or utility room inside. I am the one who would have to check on the pipes and I'm not keen on crawling through a small door on the outside as I am a plump, middle aged woman. Also, does anyone have ideas on how to keep pipes from freezing? I know about heat tape, but electricity in rural areas can go out in storms. Any other ideas about accessibility in manufactured homes will be appreciated.

If the house is designed for it, you can have all equipment (water heater, furnace, etc) in the house utility room or garage - not in the crawl space. The only thing left would be, as you say, pipes.
Crawl spaces can be insulated. Pipes can be insulated. If the crawl space has plastic put down on the "floor", it need not be a damp, dirty place. One or more lights can be installed in it as well.
As to access to it from inside the house, I don't know about that one. There may be rules and restrictions. I suggest you ask a builder.