Foam mats?

I have bought a cheapish self inflating mattress from Anaconda. About $100. Looks ok and pumps up to 3.8cm. I tested it on the floor of my garage and seems more comfortable than I would have expected. Not brilliant, mind you.
Having said all that, I am a pretty heavy guy (114kg) and sleep on my side. This puts a lot of force onto narrow areas of the mattress. I have been car camping a lot, and I know from experience that most of the cold comes up through the floor. I camp in Queensland (around Brisbane) so not that cold - no snow or anything, but still pretty cold. So this area is of major concern to me.
I had not really given foam mats a thought - thinking they were an outdated technology. But they might be a good idea to supplement the self inflating mattress. I understand that I should only look at closed cell foam, but that is as far as my knowledge goes. My gut feeling is to go as thick as I can, but most seem to be 6-10mm. I have also seen some with an aluminum layer on one side. That also seems a good idea for insulation purposes. These seem to go for around $30 or so and weigh 0.35kg)
And then there are the dearer specialist items. Like the Thermarest RidgeRest Solar Sleeping Mat (0.74 kg), which is a silver looking mat that is in a hatch sort of arrangement. They seem pretty nice from the pictures. $80 or so. http://www.cascadedesigns.com/therm-a-rest/mattresses/camp-and-comfort/ridge-rest-solar/product
There is also the Klymit Inertia X Frame, which is a 0.3kg blowup mat with holes all over it. In fact, there is only mate in certain body areas.It seems you can put it inside the sleeping bag, which seems a top idea. About $70. https://www.klymit.com/inertia-x-frame.html
I have read of down filled mattresses, but have not actually seen any.
There are also the general inflatable mattresses that I did not even look at when I bought my unit. They seemed pretty big and not for hikers. I could be wrong.
Does anyone have any comments on all this stuff? My first impression was to go with a simple EVA foam mat for $30 or so, but I like the idea (if it works) of the aluminum coating on one side. Or even one of the dearer options if that is the best way to go.
Having said all that, I am a pretty heavy guy (114kg) and sleep on my side. This puts a lot of force onto narrow areas of the mattress. I have been car camping a lot, and I know from experience that most of the cold comes up through the floor. I camp in Queensland (around Brisbane) so not that cold - no snow or anything, but still pretty cold. So this area is of major concern to me.
I had not really given foam mats a thought - thinking they were an outdated technology. But they might be a good idea to supplement the self inflating mattress. I understand that I should only look at closed cell foam, but that is as far as my knowledge goes. My gut feeling is to go as thick as I can, but most seem to be 6-10mm. I have also seen some with an aluminum layer on one side. That also seems a good idea for insulation purposes. These seem to go for around $30 or so and weigh 0.35kg)
And then there are the dearer specialist items. Like the Thermarest RidgeRest Solar Sleeping Mat (0.74 kg), which is a silver looking mat that is in a hatch sort of arrangement. They seem pretty nice from the pictures. $80 or so. http://www.cascadedesigns.com/therm-a-rest/mattresses/camp-and-comfort/ridge-rest-solar/product
There is also the Klymit Inertia X Frame, which is a 0.3kg blowup mat with holes all over it. In fact, there is only mate in certain body areas.It seems you can put it inside the sleeping bag, which seems a top idea. About $70. https://www.klymit.com/inertia-x-frame.html
I have read of down filled mattresses, but have not actually seen any.
There are also the general inflatable mattresses that I did not even look at when I bought my unit. They seemed pretty big and not for hikers. I could be wrong.
Does anyone have any comments on all this stuff? My first impression was to go with a simple EVA foam mat for $30 or so, but I like the idea (if it works) of the aluminum coating on one side. Or even one of the dearer options if that is the best way to go.