Looking forward to updates on their world adventure!
While suboptimal gear is do-able, failures in middle of nowhere in Asia/Africa or middle of desert/jungle can prove to be a a stumbling block.
Friends who toured on their C'dale had their steel framed trailer break in middle of nowhere in Austalia. Located a ranch, miles away, that had welding equipment and fixed it . . . for free. Oh those crazy Yanks pedaling across Australia on a 'push bike with 2 seats!'
In China had a component that needed to be replaced. Handed the broken part to a bike repair set-up at an open-air marketplace and 24 hours later they had a bit crudely fashioned, but workable, replacement.
Keep an open mind . . . but there can be surprises around the corner!