[Then again, I know I need to work on my climbing - that's one of the plans for the winter.
Actually, I think your climbing is pretty good. Climbing is mostly about finding a rhythm and some mental strength - you have both of those.
The problem last weekend appeared to be that you started each hill (big or small) as if it were a big hill. If you have some speed going down the little hills, then your ride would have been much easier as you would have avoided having to work on the up-part.
It's really simple: power to weight ratios. You have the power, but a heavy bike really took its toll at the end. If the weight south of the saddle was less (and possibly north as well) then your climbing will be quite awesome.