I wish you success. but it is a very large gamble,IMO. Miami-Dade County is quite complex demographically.The area I live in, southwest central Dade, is heavily Hispanic. I'm 7 miles east of Aces. And although probably 90% of my neighbors are gun owners, very few go to an indoor range or any range.
My very large extended family has several target shooters and we all go to Trail Glades or Markham Park in Broward, both outdoor ranges. And our trips are minimal,perhaps 5 or 6 times a year on the average.
Even with the large gun owning population in Northwest Dade and south of Flagler Street all the way to Homestead, unlike other southern Metro areas, Miami/Fort Lauderdale is not really "gunny" territory. Most of the gun owning population has the firearm for self defense purposes only. Few are target shooters and almost none are hunters.
On the rare occasion I go to an indoor range, I meet a buddy, who lives in Pembroke Pines, and we go to cheap Big Al's in Hallandale. It's a bit grimy,the 'hood is dicey but the prices are right and the staff is decent. Most days!
And 25 yards is important to my mind. Nothing less. Lanes should be decently spaced. The number is a difficult calculation. A dozen? 15? 20?
Aces has 16 lanes, $9 a hour if you bring no ammo.$15 if you do. Big Al's has 18 lanes and is priced about 30% less,IIRC. Both are 25 yards.
If you proceed,the location should be along the line of South Dixie Highway (U.S 1) south of 57 Ave (Red Road) to S.W. 136 Street (The Falls Shopping Mall). This strip of asphalt is above average $ wise and your base clientele will be anything but riffraff.
This location,IMO, gives you the greatest chance of success. It centers you in the heart of gun owning Miami.
And near me! My 43 member extended family will certainly be on hand occasionally. We all live within 8 miles of that South Dixie line.
I've been here since 1950, except for military service and a bit of wandering about the country. We do know this town and how it thinks.
Again,my very best wishes on success. Life is a gamble. As the wise man said,"Nothing ventured,nothing gained".