An inexpensive crank change would be a square taper MTB triple. That with a new BB with the right length axle , lower the fd, would be easy to do. There are even new Shimano alivio I think, 42/32/22 for 50 bucks ish , so would lower gearing easily.
A good quality Shimano BB is 25, installation of this stuff is fast and easy, friction shifting easy. Existing fd probably will work, but if not a 30 buck fd will do the job.

Myself and others have toured a lot on these MTB triple and they work great with a load, especially in up and down terrain.
I love this setup for loaded touring.

Look into this option.