a couple of things to think about....
First.. get up in the attic and make sure your trusses or joists are straight and you have the full width to deal with...i.e. they are off center. that is a go /no go, right there.
Second what thickness of sheet rock do you have? I think mine was 5/8. I think some older stuff is 1/2. Why does this matter? Because the fixure is only 24" at the face. It narrows about 3/4 inch or so from the face (lense). This is why they will usually fit in between a 24" on center, spacing. You will have to trim the corner of the joist/ truss around a 1/4" square. This can be done by trimming the sheet rock back slightly by scoring with utility knife. This is so you don't cover your self in sheet rock dust. I used a circular saw set to the right depth and a sharp chisel. I could see a router doing this nicely though(I didn't have one at the time).
This took a while, was a mess, but looked good when i finished.
Two problems I can see happening. Newer fixtures could be built different at the lip(mine were salvaged from a hospital renovation and were fairly old. Find the one you want and measrure CAREFULLY.
AGAIN the joists may be too close together to place a fixture. Measure each Location where you would like to put one, INDIVIDUALLY. Your framer may have drank his breakfast that morning
Just measre very carfully before you even take the trouble to purchase one. I'll get a picture later...