Bill,,,its a nightmare,,,,
you need to consider comfort,,size,,thickness,,,and the latest one i mentioned ,,the Trial pro ,,has excellent coldness rating,,,look it up on ebay,,,ive put item no up....
For you bill,,you will have more choice as you are not as heavy and fat as me,,,so you will get the comfort from a thinner mattress !!!!!,,,hence you will also get the small pack size !!!!
I'm thinking about biting the bullet and getting the trial pro,,,
never had a pro before