OK the concept of MH approval makes sense (well, I posit that it made sense in 197x...). However, before worrying about mobile-home vs non-mobile home, look at the application. Is this a 800 sq ft singlewide? Or a 2011 1800 sq ft triplewide modular built ot IRC (then, the MH issue is moot, but you might have to argue that). There are folks in 600-sq-ft stick-built homes that probably need an OAK more than a large, well-built mobile home. What is your mobile home? What is the construction, ceiling height, how well insulated and sealed? As mentioned, many here will not advise going contrary to code - though that presupposes there IS a code that applies in your case. Typically, code involves the NFPA, municipal or county code, NEC (electrical), and whatever your insurance company requires. Not all areas are subject to all types of "code", there are still, for better or worse, areas where the stupid may still legally flourish in blissful ignorance.
As with any other question on the forum, the more info the better - post some more info on your home, year, size, floor plan, etc. No one is likely to advocate installing a non-MH approved stove if you have a mobile home, but I would first establish what the factors are that make it a "mobile home" and see if they apply. Is it standard construction on a full basement, or a tin can on wheels? I agree, you would best be served by installing a MH-approved stove with an OAK. But you know best your situation, and I would hope folks here will be more helpful than "just don't do it!". Sometimes ya gots limited options, so need to do what you can for your family like aaronl said. Just be safe and continue to ask for advice. I'm sorry you will probably get some here that refuse to help, which is unfortunate - not all have the luxury of affording a new stove, or a new home. But if you can swing it, a little Englander or something would be pretty reasonable, and there's a tax credit til the end of the year, and you would have a stove that can be installed to comply with whatever code you need.
I had an Englander in a 12x50 singlewide for a while, which was MH approved and I simply cut a hole in the floor under the hearth, added a hose, caulked it and it was an OAK. The install, chimney, clearances, insulation value of the hearth, etc. are (IMO) much more serious considerations than whether your home has 2x3 studs on 24" centers or 2x4 studs at 16 " (old HUD standards vs modern home construction).