I think that your objectives for the onboarding process are very sound. But it's difficult to find external programs that match the earning rate of Hive.
One way that works for me is to generate a little crypto from activities that I would do anyway. Especially, sMiles walk-to-earn and Club Bitcoin from Thundr, which is a few Satoshi from playing solitaire. It's only about 1 Hive per week. But it's no extra effort because I'm doing it anyway.
Perhaps, collectively, we might be able to create a catalog of external revenue sources that can be used for funding this process? Because I believe that the referral revenue could be significant once enough newcomers are onboarded.