That population will work just fine.....I've had that exact setup minus the pleco
Get three cories as they like to school....the same for the neons,i've got four in my 29g.
I've read here that the gourimi need to be either one or three for territorial reasons,but I've got a pair and they are great tank mates.
Also....I was told that some gourimi are more agressive than others at the pet store.They had them seperated between semiagressive/community tanks.
Now,I don't know how true that is...but I wanted the ones in the community side anyway,so it was easy advice to follow.