For the ultimate this is just hard to beat. Pricey, but I saw several of these setup for GSSF outdoor matches and they are very impressive with their modularity and made in USA to boot.
https://www.s3rangecarts.com/collect...tol-range-cart
I agree that rectangular bags are a pain and for me so are backpacks. I want wheels. I just go to the orange big box and grab a Husky bag that suits my fancy and usage. They have a pretty deep selection with a lot of organizer gizmos. Then there's Packout, Dewalt, Ridgid and others, but the Husky bags are hard to beat for the price.