Those wheels are tougher than they look. We have a customer riding around on that same bike and he is a bit over 250lbs and rides harder than you would think someone of his size could (ex motocrosser)

Especially for short tours I wouldn't worry about it at all.

As for gearing the lowest you would be able to fit is a 28 tooth cassette and there is no smaller chainrings out there that I am aware of. The easiest and cheapest thing to do is get a shimano deore or slx rear derailer and 11-34 mountain cassette and you will have all the gearing you could as for on shorter tours.