I rode in Oregon last August with my brother – fantastic riding, you’ll really enjoy it I reckon.
We mainly rode around Hood River and Bend. If you can get a copy of the ‘Kissing the Trail’ guidebook then that’s probably your best bet. Loads of route options in there, of various lengths and difficulties, so you should be able to find some stuff to do with the trailer, as well more technical singletracky stuff.
In Hood River, check out the post canyon series of trails that’s to the west of the town. It’s about 4.5 miles outside, so easy to ride to.
Around Bend, we did quite a few trails, including iirc Surveyor’s Epic, Gunsight Ridge, Dog River, Paulina Lake ridge ride etc.
If you go to Bend in August, take lots of water! It’s high altitude desert, and the temps were pushing upwards of 30 degrees by 11am when we were there – little wind either.
Re bikes – I used my P7 with 130mm forks, my brother used his Santa Cruz SL. No problem at all, lots of fun.
HTH