So you would say it's worth to go for a few Leo Tokens? It seems they are cheap atm.
I think this part of the above quote is a pretty good idea. Include extern interactions and temporarly reward them from the reward pool. If they sign up in a certain amount of days after getting the reward -> Grant the rewards permanently. If they don't sign up within x days -> transfer the rewards back to the pool.
In a general view, can you rate how much of work it is to implement such a function? Sounds like an easy job to me, but I know I am wrong about this sometimes ^^