I would say that you basically need 5 starters minimally. So I would use this as a building project. I would try to sign 5-7 guys who have good potential ... that still leaves you 4-6 guys to sign next year.
One can play zone with 8 players on a regular basis ... easier with 9 but it can be done with 8. In fact, I did quite well with 9 players and always using 3 as a buffer to sign better players at Mississippi State
in Wooden (Seasons 63-68 ... then I stopped playing due to work related time constraints).
During that run, I tried to keep 2-3 open scholarships every year and sign 2-3 players on 5-6 scholarships with of money, effectively doubling (up to 2.5 times actually) the amount I had for each player.
It does mean that you have to play young players all the time and you have many early entries ... but at Div-1, the only way one can complete with the "A+ prestige teams" is to recruit "2 or 3" with "5 or 6" spots worth of cash as you have to get the top players to compete in the tourney at the Div-1 level.
It is easier to sign better players at Div-3 and Div-2 so you likely do not need to keep scholarships open to do a 3 for 6 scenario there, though it should work at those levels as well.