I agree with all of that - leave to clubs. But you use Nevada as an example but Nevada plays HS in the fall (at least according to this:
https://www.niaa.com/landing/index) so there is only a full match in the spring when the club schedule can line up. ECNL has managed that so I assume that the new league can. But it’s also why some ECNL teams have a complete league season played entirely in the fall or entirely in the spring while the CA teams have had a relatively balanced schedule. I’m not saying it can’t be done - I’m an advocate for it to be done by ceding league scheduling time clubs - but I’m saying that if scheduling is centralized (like for all or nearly all of DA’s existence), it’s a harder task and one that US soccer did not seem interested in taking on although it may have balked for more publicly-stated philosophical reasons re the “evil” of HS sports. I’m also saying that too often on these boards, especially California-based ones, the assumption is made that the HS soccer season for everyone is the same so it should be easy to work around. If people don’t take into account that other states don’t, or even can’t, play winter HS, the scheduling tends to be portrayed as overly simple when it is not. And last, any league can expressly permit HS participation during the club season but unless a specific state’s HS governing federation (cif for us) allows it, what the league rule says becomes largely irrelevant because kids will likely have to choose unless they want to up their risk of injury by playing simultaneously (as I mentioned elsewhere, even if a state permits it, playing what would likely be a 7 day/week schedule for a couple of months, with week after week of 4 or 5 games, is unhealthy).
This is NFHS’s link to the different state dates (at least for the current academic year):
https://nfhs.org/media/1018591/soccer-state-association-competition-dates-report-2019-20.pdf.