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.