Can I pull an carry these items in my 2003 suburu forester

I have a 2003 suburu forester am going to be traveling from San Antonio Texas to Winston Salem North Carolina I'm going to be pulling a 5 x 9 U-Haul trailer with a washer and dryer also inside the Subaru I'm going to have some boxes of clothes inside and one passenger..... I know it is not recommended at all but would it be OK to put a queen size mattress strapped down on the top really really good if I drive 50 to 60 on the speed limit will it be OK I don't want to burn out The motor or anything but I will drive really slow I just want to know if it will be OK for the car