Yes, you need a sponsor to be put up for membership, but if you don't have one, simply call the secretary of the Lodge you wish to join, and I bet there will be a way.
Yes, they want you attending meetings, participating in events, supporting their charities, etc, etc., etc. but it is my experience as a 7 year member that you can be as active or inactive as you wish. Usually there are no pressures, but as in my case it was easy finding what worked for me. Also, many of the Lodges have camping clubs who go on monthly trips together
Good luck and happy travels.