Your sales numbers are right but remember that they are an average of all manufacturers. I had a copy of the breakdowns between the various towable manufacturers and models recently. It showed some real variations between the various manufactiureres. For one thing, Tiffin is up something like 23% over the previous year and they are still running backlogged on production, even after expanding their manufacturing plant. The Phaeton was shown as the number one selling diesel pusher of all manufacturers. But, the vast majority of the maunfacturers were down.
Discounts will vary, but according to a number of conditions, not just the market. Otherwise Tiffin dealers could actually command a higher price, but that won't work or else they won't sell very many.
In reality, the internet has pretty much leveled the price field to somewhere in the neighborhood of 25% discount from MSRP. This will vary somewhat according to dealer, what they have in stock, and how bad they need to move it, but that doesn't leave a whole lot of room to offer any additional "big" savings over the normal price unless the factory comes up with a real "we're hurting, let's deal" kind of program for the dealers. If you get a dealer who's normally going 26-27% off I wouldn't expect to see any more but if you have a dealer who normally gives 22%, then you may see some extra savings when business is slow.
I've never purchased an RV at a show or rally. If the manufacturer has additional discounts available to the dealer, you may indeed get a great price on a show special. We recently ordered a 42' Allegro Bus but it was from a dealer, not at a show. We got an extremely good deal from them.