I'm in a similar situation and here's what I've learned so far. My wife and I purchased a 7.5 acre tract where the parcels ranged from 5 to 8 acres. There are deed restriction that run with the land that were set up by the original owners when they subdivided it (about 1-page long). The wife of the original owners is still alive and she is the "Grantor". Things like house plans, excavation, putting up fences etc. are supposed to be approved by the "Grantor" or if she dies her descendent's or assigns. Before I even considered purchasing it I had her sign off on several things like not having to build on it for four years (or there about), and being able to put in a gravel driveway instead of cement like the restrictions called for. As it turns out she didn't seem to really care about what we were going to do with the property and signed off on it with no complaints. She seemed more concerned about people letting trash blow around than anything else. We've owned the property for about a year now and from what I've seen around the other parcels people really don't follow the rules (letting trailers set out, gravel driveways, not mowing, temporary structures, etc). Also there are no penalties written in the deed restrictions if you break the rules, unlike other HOA rules I've seen. No home owners association has ever been formed and I don't believe one will ever be set up. From what I can tell about my neighbors they all seem pretty set in there ways that no one is going to tell them what they can and can't do.
When we do go to build, however, I will get the grantor to sign off on our house plans. I'm not stupid enough not to. You're always one lawsuit or medical illness away from bankruptcy.