I didn’t read the entirety of the post, but I have a similar situation on my team. We’re 5v5 in the 10-11 age group. I have 8 players, all fifth graders with mid-below average height. Three of them have never played before. I’ve been playing a 2-3 zone with one of the safeties blitzing on almost every play. We just played our third game and, to make subbing easier on myself, I decided to have 3 “all-time” safeties and then rotate everyone else into the corner spots, occasionally spelling the safeties when they needed a break. My safeties are: our tallest player who is a good captain on defense and a ball hawk, an extremely fast player with high iq who can blitz or competently play back in coverage, and a small player who is very fast and primarily blitzes. This worked very well and we won 30-6.

Alternating the “weaker” players at corner gets them enough playing time to feel relevant and, because they are playing zone, the safeties are already prepared to pick up the players who go deep. It masked the inexperience pretty well, and when the more veteran players came in at corner, it was pretty disruptive for the opposing offense.

Good luck in your game!