Contact Sonnie Hall, the Rental Director at Ricotta and Associates, located in Chatham. Ask her about 197 Bridge St. Its a lovely property right on Mill Pond, with a nice lawn leading down to the water. There is ample room to set-up a ceremony, and a tent. The vendors in the area know the house well, so they can probably help you make decisions about what you need and when it can be set-up. The best part is that it's not only a venue for the wedding, but you and your family and friends can stay there for the week as well. My husband and I got married there in the summer of 2008 and it was spectacular.
Keep in mind that with a tent, you will need to get a permit from the city for a temporary structure, but if you call the city in advance, you should have no problem taking care of it. Additionally, parking is available for guests on Bridge Street, but I recommend having someone out there (a responsible teenager, for example), to guide the parking guests.
Thank you for the recommendation Jess - I hope you and Peter are doing really well. I am very happy to assist any bride looking for a great venue in Chatham. I now with New England Vacation Rentals at 508-432-0900 and our website is www.ChathamRents.com One We have availability for June and September Brides at 33 Marcus Lane in Chatham! Up to 200 Guests allowed. Call for details or email me at Sonnie@NewEnglandVacationRentals.com