You really don't have to go to that bother, most chemists (pharmacies if you are in the USA

) will custom make you minoxidil to the formula you request if you are allergic. Don't know how much they would charge for it though, but maybe less than Dr. Lee.
However, it may be the minoxidil you are allergic to rather than the PG. I tried virtually every possible minoxidil formula before deciding it was the minoxidil itself I was allergic to, so I had to abandon minoxidil.