There are currently three different species of pleco called "gold nuggets". Some get larger than others. You will have territorial aggression without some creative decor to give everyone enough hiding places. With that said, gold nuggets are going to be more sensitive to poor water conditions, so you'd want to be very careful with them in a smaller tank like that.
While the primarily herbivore species are taking in a larger volume of roughage with their cleaning habits, so therefor putting out that much more waste, I would have to argue that the waste itself isn't as much bioload as it looks like. There wasn't a lot of digestible matter in the algae in the first place. The meat eating plecos tend to be very sedentary and really don't eat that much in relation to their body mass, even in tanks where the food is readily available as they want it.
I'm not saying you should run out and cram a bunch of big plecos in your 30 gallon, but you could easily add a couple Hypancistrus sp. L260, or LDA08, or L262, or L134, or many others. You have quite a few options still.
Barbie
