Motor home towing atv problems

[IndyEFI500]

Last weekend I picked up a new to me 1999 Fleetwood Tioga motorhome. Got it all loaded and hooked my Sportsman 500 Freedom behind. The trailer I was using was a 4x10 homemade unit that a friend had made for me. I have had the trailer for about 10 years and never had a single problem with it. On the way up north Friday night, I could not go over 55 mph or the trailer would start fish tailing like mad. The friend who built the trailer took a good look at it and deemed as I had that the trailer was fine. Today, on the way back, I left the 4x10 at my sisters and pulled the Freedom back on my 8x8 snowmobile trailer. Same problem but I at least got up to 60 mph. I have pulled the wheeler on both of these trailers behind my old motorhome and never had a problem. After much deliberation by myself and a lot of people I trust to know what they are talking about, we can only think that somehow the motorhome is creating some funky wind tunnel effect which is throwing the trailers. I would greatly appreciate anybody's input. The only things I have thought to remedy the situation so far are a sway bar which would be overkill for such small trailers or get rid of the motorhome (the wife geve me a bad look at this one). Thanks in advance for all thoughts and comments.

[Dave]

Maybe the tongue height is different? Load the trailer toungue heavy and see if that helps? I can't believe the ATV is creating that much draft to bog down a motorhome.

[IndyEFI500]

Dave:

I thought that too. On the 4x10 I had the wheeler just a touch forward of dead center like I usually do. I also tried moving it as far forward as possible with no benefit. I ran tne winch cable to as far a point forward on the tongue as I could go and tightened it down which also did nothing. The last thing I tried was to stop and raise the tire pressure from 35 to 50. That also changed nothing. Like I said it almost seems like the motorhome draft is doing it. I have also been debating buying a 4 inch drop receiver instead of a 2 inch but both trailers were sitting almost level. So far it has perplexed everyone I have talked to. I'll call the dealer first thing tomorrow and see how many gadgets they want to sell me.