Hi iceman157,
I’m sorry to hear that the floor mat suggestion didn’t work for you as well as it has for some of the other members in this topic.
I don’t know which specific door mat that Kait used and hopefully she will see your post and let you know but a rubber door mat would probably be thicker and less flexible than the Ikea floor runner that 10sChick used.
The only rubber mats that they show on their website that are 23" x 35" and are close to the $19.97 price she mentioned (they are listed at $20.97) are listed on the first page here.
ADMIN NOTE:Removed 404 page link | Archived Footprint: homedepot.com/b/Flooring-Rugs-Mats-Door-Mats/Recycled-Rubber/N-5yc1vZbnb0Z1z117a8
“Fixing” a mattress that is too soft can be very difficult and a solution that works for some people may not work for others so the only way to really know whether the rubber mat will work for you on your mattress will be to try it.
There are also some suggestions in post #4 here that may also be helpful if the rubber mat also doesn’t work for you.
I don’t know how long you have owned your mattress or where you purchased it but if you purchased it from WalMart (or if you purchased it somewhere else and you are still inside a trial period) you may be able to return it and purchase a mattress that is a better “match” for you in terms of comfort, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) which may be an even better solution than trying to “fix” your mattress.
Phoenix