I purchased a mobile home on land and it has worked out quite well. I bought it as a buy-and-hold,a so re-financing not significant issue.
Here is how the money crunches;
Financing; was harder, and I ended up with a private loan (no bank was loaning on ANYTHING in Aug of 2010 anyhow though, and I got an 8% loan - extremely fortunate). The house was newer ('87) and needed dramatic but simple repairs (100sq ft of subfloor, 1200sq ft of flooring materials, 80 linear feet of drywall, plus paint & light fixtures).
Rent - Less per sq ft BUT you get 2x the sq ft for the price. I'm getting a bit over 1% per month, which for CA is exceptional. In my case the ROI is the same as if I had bought a smaller 50 year old stickbuilt, but it's easier to rent a newer 1850sq ft 3/3 than a 900 ft 2/1. I am running about $100/mos under top market rent, but I am extremely picky about tenants (it's in the poorest county in California , and 80% of the renters in the area I won't consider). If a home is CLEAN and SAFE it is rentable. The nicer it is the easier it is to get good tenants. You wouldn't have mud driveways, doors with holes, or filthy carpet in your stickbuilt, so don't figure they are OK for your Mobile.
Insurance and Property Tax - based on the purchase price, so dirt cheap for the size of house.
Maintenance - Routine maintenance is similar (water heaters, roof, etc are all the same), BUT more damage occurs in a mobile if you neglect the maintenance. Preventative maintenance is the key - keep the house painted, replace the hot water heater before it rusts out, replace the roof when it's old, not when it starts to leak. Make sure the Belly band is kept caulked to avoid leaks. Keep your gutters clear and in good repair.
HINT: the biggest thing that screams "mobile home" is a bad skirt around the base. Doing a top-notch job on the fit and finish of the skirt or foundation goes a long way toward curb appeal. Also use NICE porch lights and outdoor fixtures. Skip the Astroturf on the deck. There are so few "ornaments" on the outside of a mobile that everything counts. Don't skimp by using the $8 porch light if you can find a nice-looking one for $35.
Ps - if you can chose flooring that makes the house kid and pet-proof you can often get a better caliber tenant (many landlords won't accept animals, while many higher income renters aren't willing to give up their pets). Get vinyl plank flooring throughout and you aren't risking $5k of new carpet to someone's piddling pup. Still get a pet deposit.
Quite honestly ALL houses are just a box of air. Stick-built, mobile, RV, McMansion, castle whatever. As long as you can make it waterproof, weatherproof, and the plumbing works you can rent it to someone. The larger and more appealing it is the more you can rent it for and the pickier you can be about tenants. (MySmartMove. Best. Thing. Ever!!!!)