chaffing from the constant changing gear & rear braking
How?
Questions apart: on long distance traveling, I always wear a couple of cycling bibs and they really help on very long days in the saddle. Mine are padded (same that I use when on the pushbike) but I think what really help is the tightness of it all, not the padding.
It helps a lot on the long motorway stretches, where you tend to sit in the same position for longer periods.
I do tend to move a fair bit on the bike on more "enjoyable" roads, and that usually helps a lot with any "sore butt" on its own - so generally no issue there.
Worth a try before creams or installing sheepskin and similar stuff (not to my personal liking because, as above, I do move on the bike while riding).

