While my vote is still for a tandem axle, one thing I would strongly suggest getting is Dexter Torsion axles. Rubber ride, independent of each other, better/smoother ride, no maintenance required. Side note if you will. My 4 place V-nose snowmobile trailer is tandem axle w/ said Dexter axles. Only 3 sleds in trailer and trailer is something like 30' long ball to tail. 2 sleds in front, 1 in rear. When traveling locally, I just drive them on, set parking brake and shut the door. Sleds do not move. I know folks will call me out about not tying them down, but that's another day as that's not my point for this thread. Point is, the tandem torsion axles are great and offer a great value to contents. Recently DW and I went on a trip that was about 300 miles from the house. For this, I did strap the sleds down, but watching the trailer, it was like watching a Caddy/Lincoln Town Car as it hardly bounced or swayed (ANOTHER POINT for Tandem axles).
