Since he's letting you use the land it would be good if you offered to either tidy it or at least help doing so. Would show willing and commitment, and also give him the feeling that you'd be looking out for his land while there. Reciprocation shows and helps build trust. As that builds he may allow you to bring a few more pals along, especially if they help in the clearup. Would probably be a good idea to keep it slightly on the downlow anyway as unfortunately when word gets out often undesirables move into an area, which is why so many landowners just blank refuse to allow ingress to their property.
Good luck with your new site, hope you and the landowner enjoy your times there.