I have had a bristlenose for about 4 years and recently added a gold nugget. The two completely ignore one another, but the bn is definitely more active now, so maybe think about a different type of 2nd plec.
Did you ever add the royal pleco? I'm curious as I have a royal plec (5-6") in my jungle of a 29G (plenty of wood too) and have been tossing around the idea of adding another pleco but different sub type.