InBand US was in the process (earlier this year) of setting up an indoor range in Columbus, Ohio- for veterans. You might check to see how that went-
https://www.inband.us/ The CMP has two indoor ‘airgun only’ ranges, and they are almost always filled, on the weekend. When I go to the Camp Perry range I see shooters traveling there from as far away as two states away. The Camp Perry air gun range is 10 meters, only. Clearly, there is a market. You could check with the CMP-
https://thecmp.org/youth/air-gun-matches/ I agree, that such a range needs to be situated near a major city. I would suggest the capitol, of most states. It would also benefit from having an affiliated shooting team- High School JROTC, etc.; small colleges even. (There are several small college teams in Ohio that I have competed against. They have no home range, and often practice in a gymnasium, using portable targets.) Portable targets, here-
https://www.creedmoorsports.com/search?search_keyword=Portable&x=0&y=0 The NRA has a range services division, and may be able to help get you started with
https://rangeservices.nra.org/ Although paper targets work well, and such ranges are relatively inexpensive to install, the kids today expect to shoot on electronic targets. At the very least, Orion scanned targets-
http://www.orionscoringsystem.com/orion/TargetList.aspx If using paper targets, you will speed things up with a carrier system. We have two points, in our basement, using these (there is a US vendor, but he is best contacted by telephone, only)-
https://www.euroshooting.eu/en/index.php?detail=G182 Commercial target systems
Kongsberg
https://www.kongsbergtargets.com/ Megalink
http://megalinkusa.com/ Meyton
https://www.meyton.info/en/produkte/messrahmen/black-magic/index.html
Sius
http://www.siususa.com/ There are some other electronic target systems out there. I have never shot on any of them, though. I can say that the Kongsberg, Megalink, and Sius are all reliable. We use Sius, exclusively, and have two electronic firing points, as well.
If I think of anything else, I will add a follow up post.
Best of luck!