Give PayPal A Refillable Pool Of Money Not Linked To A Bank Account

I’d like to buy things online with PayPal without using my "regular" bank account for security reasons. Heretofore I’ve handled this with prepaid Visa cards, but it’s getting cumbersome to buy new ones, activate them, link them in PayPal, keep track of their current amount, and sometimes have issues for individual cards rendering them unusable.

What other options are there to allow me to give PayPal some limited pool of money (like, $50 as a default) and then add to that as necessary, without linking actual bank accounts or credit cards?