When you go to appraoch a landowner for permission, wwear neat, clean clothing. It may sound chinsy, but first impressions are the ones that last.
Too formal will be a mistake, but a tucked in button-up shirt will go a long ways with fitting in with most of the farmers/major landowners in my area. Most I've grown up with work their butts off for a ridiculous number of hot hours in long-sleeved button up shirts and jeans or khakis depending. No dress clothes, but not sloppy.
I'd also say try to expand the contacts you have. Stop by just to say hi and help out with whatever work they're doing, but be sure to not get in the way. If it seems like they actually like you, try to socialize with them. In this area a lot of the local farmers go to bars at similar times, or they go have breakfast at certain places. If you take a guy out for a drink at the right time you'll instantly make a ton of contacts. Of course, if you come off that you're using everyone you're screwed in the community.