Yes, it's very packraftable. Ive done the Traps about 8 times from Victoria to Norwich Rd. For your trip now- do you have a mountain bike? Take it, please! stash it along Norwich rd, return via the 2 track north of the trail. Easy 10 mile mountain bike simple shuttle. 14 miles hiking, then you don't have to backtrack. Bummed, wish I could join you. Plan on a dry camp up high on a ridge for killer views. Constant water sources every 2 hrs, don't carry alot of water.
As for the W branch, we canoed it as our return shuttle in 1st wk of June, water was still good. This time of year would be low. Very good though for all of May and June.
Some good class I and II.
Here's a link to my trip 2 yrs ago.