The Treks with Bontrager rims should be fine, I use Select rims which a few of their bikes use. You said WTB rims, so is this an older 7300fx with heavier wheels. The tires that come on models until the 7.7 seem very wide, usually 700x32. I have 700x26 for road until they wear out, then i'll go to 700x25.

I think lighter wheels, smaller tires, and if there is not enough change.

Bontrager dealers have a wheel test program where you can try Bontrager rims on your own bike. Maybe try lighter wheels. Also a gearing expert may know if your gearing isn't right for you. My bike has 44-32-22 and you might have 48-38-28 according to Treks last year model. IIRC you should require less turns to go further, but someone else would know better if thats a factor. I do a one mile circle for excercise at a steady pace for 20 miles per day. I can do 20-30mph when it kick it. We both have 1--32 cassettes, Trek site says 8 speed, mine is 9 speed.

Keep in mind you said the size is wrong too, which can affect things.