Hi Matthew44,
I don’t have any specific suggestions because there are many that would work well but post #10 here has more about choosing a steel bedframe.
The Serta Stabl-Base Ultimate Bed Frame that mattressseeker would certainly be a suitable and very strong choice although there are also other heavy duty steel bedframes that are very strong in a similar or lower price range.
I’m not quite sure what you mean here. The polyfoam in the Alexis is 2.17 lbs and is a very high quality material and certainly wouldn’t be a weak link in the mattress. The comfort layers in the Alexis are Talalay latex which is the most breathable of all the foam materials. The breathability of the support layers isn’t as significant an issue as far as temperature regulation as the comfort layers (see post #2 here for more about all the variables that can affect the sleeping temperature of a mattress). Polyfoam is also “stiffer” and less flexible than latex so it wouldn’t have the same tendency to sink through larger gaps in a support system so gaps that are a little larger than what would be suitable for latex would be fine.
Again I’m not quite clear what you are asking but latex is among the most breathable of all the foam materials and Talalay is generally more open celled and breathable than Dunlop but both are more breathable than most other types of foam.
Phoenix