Would you want gun ban activists "doxing" by photographing and posting on some twitter feed, all your costumers? IS NE really more convenient that the many NoVa and Md ranges which ar just as close for most DC residents and likely subject to way less prohibitive and expensive regulation (both for the range and the customer)?
If you have a single firearm for you and your wife, which she is allowed to use in lethal threat emergency and allowed to possess at range in Virginia: Do you want your wife subject to felony conviction if she is inadvertently carrying locked and secured range bag with either unloaded gun or a round of ammo though the parking lot of this place to the car? (you'd be subject to felony as well for conveying possession). Even if you have two guns and put them both in one bag, who will carry it? If you have four bags, one for each gun, and one for her ammo and one for yours, what if you mix them up carrying them?
If you are going to spend a morning at the range with another pal from DC and one from Maryland or Virginia, how can your friend from Virginia bring their gun? Even if they bring no gun, can they legally use your gun or a range rental at the range? If you as a DC registered owner buy the ammo for them to use are you committing a felony by transferring ammo to them at the range?
This range will NEVER ever happen without broad and profound unlikely changes in DC gun law.