Tent camping

Colorado is a big dang state with millions of acres or wilderness. Pick a spot!

Steamboat Springs KOA would be my choice

There are a number of forest service campgrounds in the area of South Fork, near Wolf Creek Pass, and up toward Creede and Lake City, that have tent camping near the Rio Grande, the south fork of the Rio Grand, and numerous lakes.

We have camped a number of times in the South Fork area. Lotsa fishing above Wolf Creek Pass ski area.

One advantage of tent camping is the much greater variety and availability of camping spots. In many developed NF CG's there are always some sites that are designated for tents only. Plus if you don't need the amenities like a toilet or a picnic table, the whole world of boondocking locations opens up to you. (Do be aware that in many counties right now, you can't have a campfire outside of a designated campground.) Many great boondocking locations here in CO are on roads something like a Subaru or a RAV4 can navigate but not many RVs will venture on.

So if you want to camp for free, check out https://freecampsites.net/. Lots of ideas to get you started.

If you want a forum that is more focused on tent camping, you might try out the REI Conversations page. Some of the threads are definitely focused on the hardcore outdoors person who may be backpacking the entire CDT or free climbing in Moab, but there are sections devoted to camping locations and ideas. Go to the search box and type in Colorado and scan down the list.

You might also search for a forum that is directed at fishing Colorado.

Not knowing what kind of camping you do, where you live in CO, what vehicle you are in, etc, some ideas include:

Flat tops. Lots of lakes up there. A variety of access points. The area around Trappers Lake did burn some years ago so it still may not be the best place.

North Park. A lesser visited area but I've heard from expert fly fishermen that it's the place to go.

Grand Mesa. Again, a lot of lakes up there with lots of mosquitos to match in the spring and early summer.

There are a variety of fishing opportunities around the Upper Arkansas River Valley. Float a river, use a canoe on a lake, wade into a high mountain lake, or fly fish one of the streams. Busy place, though. Look to boondock if you don't already have reservation this summer.

Do be aware that fishing can be virtually non existent if you get around old mining districts. The water flowing out of the abandoned mines often has high concentrations of heavy metals, although remediation work still continues to try to clean up these messes.

I would suggest the OP visit the Allstays web site. The app is fabulous and inexpensive.

Bait or fly? Catch and release or for keeps? My advice would be to find your kind of fishing, first, and then choose a campground near that fishing spot.

Maybe talk to your local tackle shop??

Cottonwood Lake. The campground if you need a table and want to spend money. Plenty of dispersed free sites along south cottonwood creek. A variety of lake and stream fishing.
https://www.youtube.com/watch?v=JYheV2jjEG8