Mostly two and three gallon plastic pots, although I had some figs that were from air layering which were in seven gallon ones. I wouldn’t be concerned with yours being in five gallon, and being that they are grow bags it should help with the errant root that I discovered had escaped from a drainage hole and had to be cut in order to move (mostly fig but pear as well).
The way that you are doing it sounds great. I had mine behind a fence panel that provided afternoon shade and it worked out excellent. If you ever need additional buckets, especially in larger sizes, don’t be afraid to go beyond the free pickle buckets that you can get from every fast food hamburger or chicken sandwich restaurant.