This, 100% this. Of course, I think you could also work with other fish/organisms that process pleco waste (shrimp come to mind), to help reduce the bioload more, but from what I understand, plecos're gonna create a large amount of waste. You could probably modify it a bit more by making a sump to hold the biological filtration and going barebottom, so the waste either gets washed into something that you can easily replace (like polyfilter/filter floss), or wash (like a filter sock) to help with water quality.
One thing I'd like to add: look into Repashy Morning Wood and Repashy Soilent Green. I haven't used those with plecos, but otos love soilent green.