VPS's TOSes almost always mention "No Torrent trackers" and if they're okay with it, they only want it on dedicated machines.
My torrent tracker will require very little resources as it'll host a single torrent file that I created and own all the rights to and there will always be zero seeders so the torrent tracker won't actually be transferring any data. Yes that's not how normal trackers work but I can't give out more details except to forget all the assumptions you have about regular torrent trackers and that this torrent tracker won't be a resource hog.
█ Charles W. @ Nexeon Technologies, Inc. - Have a question? PM or email me directly! - c[@]nexeon.com
█ Dedicated servers, colocation, cloud, game servers, on-site & remote DDoS protection, and more! Managed options available.
█ Data Centers in Chicago, New York, & more! IPv4 and IPv6 available! Contact us for data center buildout & network consultation.
█ InstantDedis.com - Instantly delivered dedicated servers located in Chicago, New York, and Dallas.
Although a provider may state right in their ToS that they do not support it, most do this because it is often abused. I'd recommend going ahead and contacting providers directly to speak with them, explain that the resource usage will be low, and that they should allow it. Your best bet if you want any stability would be avoiding any provider that would allow you to do this, and do this on a 5$ VPS. A provider that allows this probably wont have stability in their mind.