Need Help white on vinyl

Hi All, We have an EFI-16H printing on Vinyl for an awning. Need an opaque white for lrttering and the machine has 3 levels of qualitly (in other words speeds / # of passes of print head) that will sort of work.

The lesser of 3 "POP" is awesome for speed but not white enough. Next better "HIGH" is almost good enough and decent speed.... The "ULTRA" ode is awesome whiteness but super slow and cant bet done at a profit. and too slow for shop... Is there a way to trick the file to print withe as a background AND as a color to get a double hit at the "POP or High" mode to get more white at a better speed?

 

no - not just overhead lights and sunlight.... its is opaque colored vinyl printing on the first/front surface

 

Yea i was afraid I knew the answer... was hoping that I could trick the machine to print the white the which the machine will put under a color as a foundation but then come back and print it again as if it were a color on top too... wishful thinking
Thanks for the feedback all