Hey Rip!
I hope all is well. I have the same RTT model that you have and experienced the same issue that some people here are describing with the mattress. Could you provide more details about your 2" memory foam pad and the mattress cover?
BTW, I received the brackets just in time for our trip this past weekend. Muchas gracias! Here is a picture of us test fitting the tent for the 1st time on the Disco after I had to fabricate the front crossbar to support the tent. This roof rack is not designed for an RTT, but after the modification, it worked. We went to Toro Negro Forest up in the mountains.
Hi Tony, so, you found out the shortcomings of the stock mattress, eh? I found it the first time I test flew the tent in the driveway...
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Anyway, I found my 2" memory foam mattress pad on overstock.com ($75 shipped!). For my Gran Sabana I ordered a California ("Western") King size. Fit just right (about 4" back from each edge of the stock pad). So, I could tell that the memory foam pad wasn't going to fit into the supplied cover. So I Googled "mattress pad covers", and found a moisture resistant Cal King cover that fit a 6" thick mattress pad. I keeps both the stock pad and the memory foam pad together nicely, just stuff them in the new cover (a real PITA!) and zip the cover closed - Done!
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I had been asked why I just didn't get a 4" memory foam pad. 2 reasons: 1- They are NOT light. Even the 2" is about 40#. 2-Memory foam pads don't give all that much support, unless they are really thick.
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I also added a heat-reflective survival blanket under the mattresses for cold weather camping. I think it helps a tiny bit.
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HTH!