A second layer of blocks sounds like good idea if you don't want to bend over to much. Anyway you should also rather bend your knees as much as possible and lift with your legs. If you have not heared about the "Back to Eden Gardening methode you should really check it out. Here is a post that I wrote about it with 2 videos to learn how to implemate it in your garden. Good luck with the garden and keep on growing :) https://steemit.com/permaculture/@softfuture/how-to-get-free-woodcips-for-organic-groundcover-in-your-organic-back-to-eden-garden