Another Consideration
One other consideration that hasn't been mentioned yet is you tow vehicle. A vehicle with a longer wheel base will all less fishtailing. I don't have any at all with my new tow vehicle. I started with a Ford F-150. There was a little sway in the trailer at 70 miles an hour. What really started to play on that truck was the milage and the fact the transmission was going to go because of the stress my boat was putting on it. This summer I got a Ford F-350 Diesel. It is a huge difference. I don't even know that the trailer is back there. I get better gas milage when towing. Another advantage is that I went from a regular cab short bed F-150 to an Club Cab long bed (thus extending the wheel base quite a bit). Now I don't get any fishtailing either. The longer wheel base and increased weight of the tow vehicle make a huge difference in regards to fishtailing.
One other consideration that hasn't been mentioned yet is you tow vehicle. A vehicle with a longer wheel base will all less fishtailing. I don't have any at all with my new tow vehicle. I started with a Ford F-150. There was a little sway in the trailer at 70 miles an hour. What really started to play on that truck was the milage and the fact the transmission was going to go because of the stress my boat was putting on it. This summer I got a Ford F-350 Diesel. It is a huge difference. I don't even know that the trailer is back there. I get better gas milage when towing. Another advantage is that I went from a regular cab short bed F-150 to an Club Cab long bed (thus extending the wheel base quite a bit). Now I don't get any fishtailing either. The longer wheel base and increased weight of the tow vehicle make a huge difference in regards to fishtailing.