I highly recommend this mod.
Clearance is the only issue that can be a problem.
You need a minimum of 3" from the top of the tires to the wheel well, and 1" between the tires.
If you are lacking in wheel well clearance, a lift of some sort, either a axle flip or lift blocks or a combination can be used. I have done all of this on different TTs.
As for the 1" between the tires, that would be more difficult to fix. It would involve welding on new spring hangers and using longer springs. I would have really be in love with a TT to go that far... But I would for the right one.
As for the 1" minimum... That is what Dexter recommends. I have gone right to that limit, though I don't see why it couldn't be fudged a little. As one wheel goes up the other goes down and that distance increases. So what ever clearance it has when level is the least it will ever have.