Heat transfer vinyl for motocross jerseys

Hello, I have been doing motocross jersey number lettering with standard thermoflex contour cutting for a while and recently purchased a Gerber Edge system. I am having trouble finding material I can print & contour cut that will block the dye migration from the sublimated jersey. I have tried to first press an underbase with Specialty Materials Sub-stop & print on "color print" & apply. Only issue with that is it a bit on the thick side and not so flexible. Has anyone come across a material I can use without layering... Keep in mind it has to be 15'' wide and punched to work with my equipment.
Thanks in advance.