Originally Posted by
CliffordK
It would be easy enough to design a bag with either padding, or a molded back that might even be designed for optimum weight distribution. However, the bag would loose compactness.
A pocket in the bag where you can insert what you want for suppurt. Cardboard will do and can be thrown away when you no longer need it. An inflatable sitting mat (like the sleeping mats but smaller) if you need comfort. A pocket like that is easy to make after you bought it.