Ben Siegal had 5.2 hatched from field-inseminated females recently. They were in the classifieds right before the Colubrids section was split into separate groups. You could check on his website - albinonile.com.
I have a male that came from him and it's a very healthy specimen. The rest of mine are acclimated imports and few of them do as well as that male.
Long-term captives are a rare find.
Gonyosoma seem to do well in a variety of setups. I know of one breeder who produced fertile clutches from pairs housed in 28 qt. rubbermaids. That would not be my first choice but it does not surprise me that they did well in such a basic setup. I'm sure he had a lot of fun getting them back in the boxes everytime.
I keep my specimens in large plastic storage boxes measuring 32" x 16" x 12". I use a lot of ventilation and provide humidity with frequent mistings and/or keeping sections of the cypress mulch substrate moist. When I move to my next place my setups will be changing quite a bit. Not exactly sure how at this point.
Some breeders keep this species harem style. Mine are still housed individually primarily so I can keep track of feedings.
Mine don't exhibit much in the way or arboreal behavior but I still recommend providing perches, etc. My black Gonyosoma janseni are much more arboreal than my G. oxycephala.
At any rate, there was a recent thread on this. It should be easy to find.