Looking to make my 11-speed road bike drivetrain more climbing friendly. For rolling hills, when fully loaded, I am in the lowest gear more than I would like, and the plan is to do some trips that involve more serious climbing this summer. What are the options for lower gearing?

The current setup is Ultegra 50-34 front, 11-32 rear, which gives around 29 gear inches. It looks like JTek Shiftmate 8 allows the use of 11 speed road shifters with 11 speed MTB rear derailleur and cassette. Shiftmate Compatibility | Jtek Engineering. This would give me 23 gear inches with an 11-40 cassette or 22 gear inches with an 11-42 cassette, either of which would be better. The conversion would run around $200.

Are there other options, such as swapping out the inner chainring or a new crank, that would be better or cheaper, and allow even lower gearing?