VPN provider is just as likely to rat as the private tracker, if it comes down to it. Only VPN I’d truly trust is Njalla. Anyway I’m interested in why a VPN is recommended for a private tracker.
On a private tracker my ISP knows the domain name of my tracker, and, the IP addresses of the peers I downloaded from. They do not know any of the content, unless they join the site AND seed the content in question.