Something I think about often.
As I made plans for a 39 year breeding program, I realized that in that time, there could (will) be designer plants.
The CRISPR process you mentioned could be applied to an F1 of P.t x citrus and delete the bad flavor genes of P.t, and delete the genes for cold damage from citrus. I presume the deleted genes of P.t could be replaced with copies of the citrus genes.
But I decided to give the old way a try, as it is the method I know and am set up for. I plan on wondering around on this Earth for several years yet, and I might as well do something interesting.
I'm told that citrus pollen properly dried and refridgerated will keep for a year. I haven't tried, as I'm mostly waiting for flowers.