foam mat roll, exactly like this, from harbor freight (or wherever).
cut it into squares or narrow strips, or micro(for easier packing).
why: save your butt. softer than sitting on rocks, gravel, or concrete.
benefit: cheap, light, effective.
cons: easy to forget (thus leave/lost risk) , often packs awkwardly.
*tip: large pieces double as shading tool eg when walking in the sun.
A convex edge makes the edge of the knife stronger. The convex edge is also called an "apple seed edge" gives more strength for more difficult/harder tasks. The trade off is that it's going to behave less "sharp" than if you have a standard v-edge. Not that it's not a sharp edge just that it won't be wickedly sharp. However, it's going to last longer than a v-edge (broadly, lots of variables here).
So, for example, woodworking tools will be a v-edge because you want the sharpest possible edge. The trade-off is some of that edge will be less stable/strong over time and you'll need to re-sharpen more regularly.