I say CPA is a losing proposition for both affiliate and casino 
Outside of that, I am not sure. I would think that you could lower the ‘bounty’ for such players, then, if it is a problem.
Like
$10-$30 1st Deposit = CPA $50
$30-$50 1st Deposit = CPA $75
or some sliding scale like that?
Now – I’m just curious and am NOT a CPA-taker, so this may not be an option. Just thought that there must be some way to negotiate with the casino for these players who start off with small deposits.