The ferry operates 24 hours. Using a golfcart gets expensive at $5bz each way. It is supposed to be free for bikes and pedestrains, but I hear they are charging tourists $1bz. From 4 to 6pm is rush hour and avoid that time. Plan to visit the Hammock House Bar and Restaurant located on the river on Sunday late afternoon. Of your selections, I would take the one North, but I like privacy and a peaceful beach with no traffic.
Small correction: the ferry is free for walkers/bikers during the day, however it costs $10 to bring your cart across after 8PM and a dollar for the cartless. Contact Caye Management for houses/apartments for rent in the Boca del Rio area. There are several great houses/apartments to rent. As far as noise goes, Boca del Rio is generally very quiet, it is a toss-up, will be great either way, North or South of the ferry!
Mitt, Casa Caracol is south of the ferry. That is on the town side of the cut. Easy walk to town. Grocery and Papi's are real close. North of the cut has never interested me, as I like to go to town every day. Enjoy!
Life is not about waiting for the storm to pass, it's about learning to dance in the rain.
Paying $10 to cross on the ferry every time I wanted to go into town would make staying in the north lose its appeal (to me at least) real fast. Don't even get me started on whinning about that road north of the cut either. Last time I was over there it gave me a nose bleed, and I'm not joking, from the whiplash action of dodging potholes. I can see why most people access the north by boat.
We were there at Christmas and stayed north of the cut. The cost for the ferry was never the same. Always after 8 pm we were charged 5 blz to go across in a cart. We were charged on Christmas during the day, but for only one way. Some days we weren't charged at all during the day to go back and forth across the ferry and some days were charged one way. The signs on either side of the cut stipulate that all charges are for after 8 pm. We just paid when we were asked, which was not often, and felt like we were getting away with something when we didn't have to pay. We stayed a little south of Casa Teritsa and I have to tell you when we walked by we had to peek in the windows - it was beautiful, nice big lot with lots of palm trees and it's own pier. It was in a section of really nice houses. If you are looking for serenity I would recommend there, however if you are into the bar and late night stuff you may want to stay in town.