Yeh, a big robust pocket for tools to cut the slabs of concrete.
Make the bag simple and a "day bag," 4 pockets one strap.
1. Large mesh bag for kite(s). Zips both ends.
2. Small mesh bag inside big kite bag for bar.
3. 4 liter robust water/sand proof bag for tools, tape...
4. Small water/sand proof bag for personals like gum, keys....
One big comfortable strap so you can sling it over your sholder with the bag always balancing perfectly. Thus, the pockets need to be centered.
Good idea sandman, the wind will come again