So I did some research and found the average number of 3* commits to each of the service academies over the last 5 years.
Navy=3.4 3* avg
Army=.6 3* avg
Air Force=4.2 3* avg
the total average between those 3 service academies is 2.7 3* commits.
So I think limiting myself to 3 3* recruits a year seems right. That along with only recruiting players with academic prestige in recruits top 3 should make for a challenging dynasty.