Exactly my intention, the question is how. Checking out possibilities.
I would consider cutting the frame just behind the BB and the cut on top would be just behind of the seat post. Those 2 areas shouldn't be too difficult to access. I would also consider cutting the stays completely off at the rear brackets and replacing them with tubes of the appropriate lengths. Is the frame steel? I think a steel frame would be much easier to work with. Perhaps you could get the needed tubing from a donor frame. Look before you leap!