Thanks caribmike, The road(s) have been noted. However, hoping someone has had experience going there. Google maps OK, but do not give sufficient eye level and road feel information.
Yes the OP takes the road to Barahona from San Cristobel through Bani and Azua. 20 or so kms after Azua he takes a right fork to San Juan....there will be a police check at this well signposted intersection. Follow this road for another 15kms or so and take the right fork to Padre Las Casas.
It looks easy from the map to find the road to Guayabal, but my recollection when staying in Padre Las Casas a couple of years back was that it wasn't signposted and I was being given directions anyhow.
At that time the road to Guayabal from Padre Las Casa was a dirt but well graded and a large bridge in construction over the river Las Cuevas. I believe some of this road has been surfaced and even the bridge is close to completion now, albeit it wasn't a difficult drive all the way to Guayabal at the time I went. Here is something recent on the roads/bridges in this area from MOPC: http://www.mopc.gob.do/noticias/avanzan-trabajos-de-construcción-carretera-padre-las-casas-bohechío/
All the roads to Padre Las Casa were good by the way.