In the manual's section "change of default settings", N7DDC mentions for cell 31 " If the power does not exceed 40 watts, it makes sense to use a tandem-match with a ratio of 1: 5 turns, which will allow to work better with a minimum power of 1-5
watts." I believe cell 31 should then be changed to a value of 05.
What wasn't clear to me was that cell 05 also needs to be changed to 01, so the tuning starts at 1W. I didn't realize this until I perused the Issues section of N7DDC's github page.
Of course, once you rewind the tandem match for QRP, you should transmit more than 40 watts, or you will exceed the 4 volt limit on RA1.
I haven't rewound my tandem match yet, so ymmv...
va3rr