Sisters to Sweet Home

As far as large vehicle restrictions I think maybe you are thinking of US 20 going in to Sweet Home. This hwy does have length restrictions, it is curvy and a little steep in areas. The good thing is that it is only 72 miles from Sisters to Sweet Home, where it is 136 from Sisters to Sweet Home taking 20 to 126 to I-5 and then OR 228 to Sweet Home which would be about 150 miles.

I have towed a 36.5 fifth wheel both ways and it is better going from Sisters to Sweet Home on US 20 then going the uphill the other way. But if it were me I would just take it slow and stay on US 20.

Oregon Highway 126 is good anywhere you are on it. HOWEVER, if memory serves me, you may find Highway 20 continuing on to Sweethome to have a rather ‘ uncomfortable ‘ drive. We took that section years ago in a 30’ Trek motorhome and found a few miles of rather steep and winding section not to our liking. We resolved not to take that route again. You may find it even more uncomfortable to drive in a 40 ‘ Motor home!
I would recommend taking 126 all the way to Interstate 5 and going to 228 to Sweethome from there.

126 down the McKenzie is a beautiful drive. Used to drive it towing my 36 foot fiver with no problem. Be sure tomplan a night at Belknap hot springs resort.