I’m not a fan of CR myself (too touristy) but I’m a huge fan of Nicaragua! Same landscape, people, food, etc. as CR, and about 1/2 the cost. $1500/mo there will be more than enough. The surf is great in CR but it’s packed with gringo’s, as you mentioned. Nica has slowly started to develop some of that but it’s a long ways off. There are still plenty of breaks where you’ll be alone in the water (or maybe with a few other people)
Nica is extremely safe. Safer than even CR I believe. Gangs / drugs are not the problem there that they are to the north of the country. The people are extremely warm and friendly.
Internet is OK. Honestly it’s slow. A good connection is about 10mbps but a lot of beach hostels, etc. will be a bit slower. I routinely work from the coasts of Nica, hold skype/hangout/slack meetings, etc. It’s fine, but if I were to try and download huge files, I’d probably pull my hair out.
I admit I’m a bit biased. I love Nica, travel there 4/5 times per year, do business there, and have become a legal resident there (mostly for business purposes). However because of this I’m super familiar with the country. Avoid San Juan del Sur (gringo’s) and you should be in store for a pretty authentic experience.