I'd make sure that account has an EIN attached and would focus on a few products with multiple quantity that you have receipts for. Then that account would be set
I don't think it would have boosted anywhere close to that high without an EIN attached. I'm even registered with my state, which I don't think hurts.
I don't think the EIN has any bearing on eBays decision for raises. I create accounts with a non-verified PayPal account attached and within 3 months the limits have been raised several times automatically that are very high