So much to consider. Glanced at population these day's (DAMN) seem the area has grown since before the cross florida barge canal day's so no worries there. Past rules,regs'permits,zoning..... ???? Figure you've got that.
Indoor Airgun range? Would people use one? YES. And a shop with indoor range works - as long as sercvice is excellent. Jim did just fine in Michigan with such. Now if your range is 10m fine, HELPS sales, if you have 50 yards, extra side hustle. Have you been to th couple of airgun FT clubs around your area?
Much to consider and anyone can become a dealer (many many have and Then realized) the mark up isn't much and from time to time even as a dealer you will be undersold by your suppliers -sales & such- so Customer Service . have repair experence?aware of warranty for every brand you might carry? How wil you be handling this? Liability insurance cost/needs? How much inventory can you afford sitting? Need to stock everything that goes with them also to keep folks happy.
Had a store 16 miles from us briefly mostly big-bore AF rigs he knew how to work on - scraping warranty in his case- but a few AA rigs, a Marauder, a ... , a ... and pellets & slugs, always need more ammo. Did not know it was there until I saw AirForce with the Squirrel painted on the side,made a u-turn & went in. Wife had a restaurant in the front airguns and Air , had two good compressors, in the back. Was really taking off and in his case would have done very well but timing with covid combined with too much overhead did him (and his wife) in.
It can be done. It is not easy.
I know of a half dozen people here who are or were dealers hoepfully they come along & add. People with actual stores not so much. As much advertizing as you can get seems important to me.
Lot's to consider.
John