Also, measure the dropout spacing without a wheel installed. There's a chance that it's already 131 or 132 mm, which would give you more peace of mind when spreading it to 135. Fortunately, the Chameleon takes 24" wheels (ERTRO = 520 mm to be precise) so the stays are not too much shorter than those made for a standard 622 mm road wheel.

I also researched about reducing the width of an Alfine hub a couple of years ago. From what I read, it's not too hard to reduce an Alfine 8-speed to 130mm, but there's not much that you can do with an Alfine 11-speed.

Since you don't have much choice, I would just squeeze the 135mm hub in there and not worry too much.