As the six-man purists on board will know, UIL had a 75 enrollment cap for years; now at 99.9 or 100 enrollment.
TAPPS has struggled with this as well, this year walking away from that cap and instead pushing it up to something like 67-69 boys enrollment (the same limit as Div IV 11 man boys). This was to allow about six or eight schools with enrollments just over 50 boys that were playing independently to play in district. It's worked out pretty well ... and from what I've seen, those schools aren't exactly wiping up the field with their opponents.
There are a number of schools, private and public, with enrollments under the sixman numbers who are able to field 11 man (aka "crowded field football") teams. Shiner St. Paul Catholic, down the road from us about 60 miles or so, has a TOTAL enrollment of something like 76 and there isn't talk from there about playing sixman anytime soon. UIL Runge HS has had some problems, even playing independent for a couple years, but they remain UIL 1A 11 man and I hear no talk about moving.
But let's remember what the purpose of sixman footbal was meant to be -- to allow kids in schools too small to field an 11 man team to play competitive, tackle football. The day I see a school (or homeschool group) suiting up 50 kids for a sixman game is the day I don't play that team.
It's kinda like the story that kept Converse Judson from spliting up their high school. At least two or three bond elections failed because folks worried that it would dilute the football talent at Judson HS. I joked that Judson needed to start a UIL 5A Six Man division and that would solve the problem. They finally did vote in the new school, Wagner, and there has been some dilution, but not enough to keep both teams from doing pretty decently. By the way, Judson ISD is now having a bond election and may build a third high school. My bet is the bond loses.
Honestly, if you can reliably bring out 30 boys (grades 9-12) on a year-in-year out basis, I believe you seriously should be looking at playing the 11 man game. But the change shouldn't be something you make lightly. I know of some schools (Austin Regents being the textbook on the move; Dallas Covenant looking to make the next step in the next year or two) who chart out the way they will transition from 6 to 11 man. Often, this is done by coaches attending some of the better 11 man football coaching clinics (and there are boatloads of them) and starting at the middle school or junior high level before playing a varsity schedule.
I've talked with the FEAST folks in the past (several years ago) and asked them why they chose 6 man over 11 man ball; this is a group that could reasonably be expected to turn out numbers large enough for 11 man (I think they get 100+ high school boys out for basketball and compete at the UIL 4A/5A level in many sports, including track, cross country and basketball). I was told they did not think they could get a schedule in 11 man ball.
As far as I know, there may be one or two home school 11 man teams in the state (I think there is one in Dallas, another in suburban Houston but that one could be at a middle school or subvarsity level).