A couple of places that have water nearby, and might have fishing (not a fisherman myself, but they look promising?)...
-- Back in 2019, stayed at a beautiful, out of the way, but relatively-developed campground along the upper Deschutes River, southwest of Bend, outside LaPine... Bull Bend Campground. Really nice campground snugly placed on a very tight bend on the river, so water all around. Roads in are fairly decent, but place is well distant from the highways, so very quiet. Apparently good fishing according to USFS, link here...
Deschutes NF - Bull Bend Campground ...and map here...
Google Maps - Bull Bend This photo is from that trip, but doesn't show the water, which is just beyond the trees on the other side of Beastly (we were there only over night, passing through)...
-- Just stayed last week at a great primitive, dispersed campground at Round Lake, outside Sisters, Oregon, a bit north of Bend. It's a beautiful little lake right below Three-Fingered-Jack Mountain. Fun bit of road getting in there from Highway 20, on the southern leg of FR 1210, aka SW Round Lake Rd (I don't recommend the northern leg of 1210, as it is horribly washboarded). Surprisingly nearly no mosquitoes for this time of year, and an amazing sunrise on Three-Fingered-Jack. Was free to camp there, but all facilities there were not replaced after a 2003 fire came through, so no actual restrooms or water supply. Might recommend looking up some reviews online to see if it's to your liking, but I enjoyed it. Link here...
Google Maps - Round Lake
Happy travels and welcome to Oregon!