I have a 60 inch tiller (3PH PTO driven) it too is not as wide as my rear wheels and originally caused me some concern but I did a garden this year with it about 50-70 ft wide by 200 ft long, to compensate for slight slope I tilled the last time back and forth the short direction so tire marks wouldn't run down hill and boy was I lucky to think of this. We have had oodles of rain and very litte erosion in the garden due to the tire marks running essentially normal to the slope.
So you see there is a plus, in my case, for leaving some tracks. The price yo give is great. If it works, and if it were me, I'd get it. If it turns out you just don't like it, you got in so cheap you could easily get out without a big loss (maybe a profit). Who knows, maybe you could whomp up an adaptor to allow mounting it off center (within the angle the PTO will accomodate) and not have a tire print problem if that is a big deal for your intended use. I am a lot less concerned now after giving it some serious use that I was before. The tiller not being as wide as the tractor turned out to not be a big deal. If it is a big deal in some appiications, I'm sure you will hear about it here and soon. Only you can decide if those applications (if they surface) are THAT important to you.
Patrick