We know of the "abrasive" method - a low-ish speed polisher / buffer with some polishing compound though tonight I came across this "chemical" method. Hmmm...
The product: CRC QD Electronic Cleaner
`listed as in-stock at Home Depot for about $10/can
Fast forward to 2m 30s for the start of cleaning
OMG! How to clean a clear vinyl window on a M151A2 soft top or any clear vinyl window.