If you're really concerned about it, you can try shadowing a DO for about a month, then ask him to write you a letter. If you're ambitious, grab an insurance list of doctors in the area and start calling DO's one by one.
It will push back the date that your medical school application file will be complete, but at least you'll have the LOR there. That's pretty much what I did. I learned about osteopathic medicine late in the game, and didn't get my file completed because of the DO LOR until January (and didn't do my first interview until March). However, keep in mind that the later your file is complete, the harder it is to get one of the dwindinling number of seats available.
I don't know how crucial the LOR is to adcoms. I know of only one offhand that require it (NSU - your file there wont be complete until they get one). I remember some secondaries saying that it wasn't a requirement.
If you decide not to have one, you may want to be prepared to answer why in an interview. I'm not saying they will ask, because I have no idea what they would ask any one person, but it might be a possibility.
Anyway, good luck!