I once asked a merchant account provider how larger companies (airlines, for instance) operate by selling stuff way in the future (booking at ticket 5 months in advance, for example), when they were giving me grief about selling a magazine subscription for a year in advance.

"Big reserves on deposit" is what I was told.

It's probably not quite as simple as that, but I suspect being able to demonstrate a degree of financial solvency (airlines? really?) and having funds in reserve would go a long way towards paypal working with you more. In fact, I think paypal ends up holding some of your funds for you as a reserve against chargebacks after certain conditions are triggered, no?