I'm with Batman, Livebearers would work well with your water and actually do poorly in softer acidic water.
I would stay clear of Dwrf gouramis for many of them are prone to viral infections and as you have noted,,they can be quite territorial.
I have kept both the Rhino or (chocolate) plecos and the common plecos as well and both grow quite large and are copius waste producers making maintaining water quality much more difficult than the smaller livebearers.
Many people purchase the plecos as "cleanup fish' and they produce far more waste than any benefit's to all but the largest of aquariums. I might trade both to fish store for store credit if they are willing ,and select a species of pleco that stays smaller but to each,, their own.