I ordered my current unit in late December. I let them know I was a serious buyer prepared to pull the trigger if the price was right. The dealer was very eager to deal. I got a very competitive price and a great trade in offer.
I think the cold weather off season strategy definitely work for me. The dealer was eager to have some cash flow. My unit was special ordered so the dealer did not have to inventory my unit very long. I got a great deal (I think LOL) and the dealer got a winter time sale. It was a win for both of us.
I don't think winter RV shopping is for everyone. You must know what you want and not have many questions. It can be hard to window shop and tour units during the winter. However if you have already done your homework and know exactly what you want. Dealers are more eager/hungry for sales during the off months.