The earliest you'll be able to cross the rivers on this route is in early December, Jack knows this area like the back of his hand, he's spent all his life there & he agrees with this.
There's a group of us that have already agreed to do this route in the coming December, we may do it twice, basically starting at Umpang, taking 2 days to ride the border trail south to Sangklhaburi & then ride the trail again north back to Umpang. Some riders have being toying with the idea of trying to do the whole trail in s day, with a fast group of riders that might be possible with no drama's (flats etc..) along the way.
We've been talking about setting up several "rides" through this trail in December 2012/ January 2013 if people are interested, the tracks for this trail will be on the next version of the North Thailand Road & off-road GPS map, as far as we know, this will be the only GPS map available with this trail data.
If your interested send me a private message.