it's kind of sad but in Milwaukie I practice at a large field where a school has closed and been converted to offices....if you can find one like this I have seen that there is rarely anyone there....I can get on a strip of grass elevated from the main field and all though there is a building and some playground equipment you can set your practice basket up up to 700 feet away! Also found a double (back to back) soccer field area with baseball diamonds on each end. This offers a great, if sometimes loose, tee and a large target.....more people at this location though due to a walking path.
Field practice helps so much that I finally have been able to get a few shots out there recently over 600 feet again....I took several years off but never thought I would throw that far again. A couple long ones came for me after warming up like many reccomend by throwing out my entire bag, around 20 discs, at my practice target from 30 percent, 50, 70, 90 and finally full power. sometimes I skip 90 cuz this can take well over an hour and is tiring. But you get so limber for me I can finally rip my esp nuke like a pro if I get a lucky release! Go for that field practice!
and good luck