I grew up in that neck of the woods. The little bit of 131 between 106 and 103 we didn't very often travel over (due to where our house was, between South Reading and Tyson), but the section between 106 and Claremont, NH I've been over many, many times.
At any rate, it should be a perfectly reasonable route for a motorhome and toad.
Depending on where you're going in New Hampshire, you could reasonably also take 100 north to US4 and then head down I-89.