HI dalbeath,
I seem to be following you around today
This question cannot be answered by anyone on a forum. It is extremely important that you discuss this with your surgeon. This is because the corneal shape tends to fluctuate markedly straight after CXL and the amount of this fluctuation is very much dependent on individual eyes. If you are wearing rigid lenses (whether or not with a piggy back system) then it depends on the original fit of the lenses as to whether they will be suitable for you to wear after the CXL or not. As they are, by nature, rigid, they are inflexible and may end up being to flat or too tight for periods following your CXL.
I fit soft lenses after CXL so that they can flex as the cornea changes shape, thus patients can wear lenses again quite quickly, usually after a couple of weeks but even then, patients tend to leave it a bit longer to be sure. If you are going back to RGPs, then you really should wait until your cornea has returned to a reasonably stable situation. For some patients this is 3 - 6 weeks, for others it can be a couple of months.
Knowing KC patients as I do, I know that they tend to listen with one ear to what the professionals say and with the other to what "everyone else does" to see what they can get away with. In this situation, you have to listen to what your surgeon says and he will not be able to say for sure until he sees how your eye settles down post op.
Incidentally, what is the thickness of your left cornea? CXL can be done even with quite thin corneas if it is previously temporarily thickened with distilled water during the procedure.
Lynn