Yellowstone is huge! It is basically divided into four sections with a loop road for each section. You should not have a problem parking your rig in most of the places you can drive to. We were there a week and did not see everything. Can't wait to go back.
West Yellowstone has several stores specializing in fly fishing gear so suspect most any of them could put you onto a guide. Enjoy one of the most beautiful and magical places in the world.
We got the book Yellowstone Treasures by Janet Chapple which is a great guide to visiting the park.
'07 Country Coach Allure 470 Siskiyou Summit #31578, Cummins ISL 425; 2014 Ford F150 toad; Air Force One Toad Brake.
Glen Allen, VA; Smith Mountain Lake, VA.