I am putting three 3-spot gouramis in my 46g with some platies the three spot's are supposed to be the more aggressive gouramis. In all of my research, I haven't seen many serious problems.
Honey gouramis should be wayyyyyyy more placid and it should fine. I would do that combination in a 20g. It really depends on how many fish you plan to keep and what ratio of males to females.
I have 2 separate 20 gallon tanks with a male Honey & a male Platy in each. One has a pair of Bolivian Rams and the other has single male Ram. They get along fine.