I've determined it's basically impossible to do that if you don't own a dedicated high-bandwidth seedbox
Completely untrue. I don't have a seedbox, never had one, and I keep perfectly fine ratios on two different private trackers. One has a ratio of 56 I think, the other (the one I use the most) has a ratio of 4.5, both just have a minimum requirement ratio of 0.5 i think before you're kicked.
I just have a computer on my home network, which is also the media server.