Joe
The loss attributable to a 2:1 VSWR cannot be stated as a constant. It is a function of the length and characteristic loss of the coax cable used.
The additional loss in 100 feet of cable that is a consequence of having a 2:1 SWR load would be 0.33 dB for RG58 and about 0.11 dB for LMR400. This is far less than 11.1% however none of the calculated additional loss are significant and overcoming those losses by searching for a perfect match will solve no problem that the author is experiencing.
Warren Allgyer - WA8TOD
Warren Allgyer