Gazebo Footing Question
I'm running into a small problem installing a gazebo and could use some advice. I'm installing a 14'x12' gazebo on my law. The lawns sloped and I am intending to use 36"x12" sonotubes for the footings. Unfortunately the gazebo feet with attaching hardware is greater than 12". I feel like 12" sonotube for this structure is already overkill and going up any larger will significantly increase the expense and difficulty. Sonotube sizes great than 12" means bigger augers and more expensive equipment. Now my idea is to use either a 10" or 12" sonotube with an inverted square footing. Picture included demonstrates what I might like to do, but Im just wondering if doing this is a terrible idea. The only bad thing I see about a design like this could be the potential for frost heave. I could also just do a tube and cap it with a larger say 14"x14" paver, fasten that to the cap then the footing to the cap.
There has to be a better way to fasten down this gazebo, thank you in advance.
edit: I don't know how to reddit well, heres the image idea https://imgur.com/gallery/footing-Um5v9PS