Try fabric grow bags, you just have to separate it from the ground.
I've determined the ideal grow bag size for me is probably 7-gallon, which is closer to the actual volume of a 5-gallon bucket. It's the right size so that the bag is not too heavy and can be carried around without killing your back.
I'm eager to try these because it have a design that let you insert sticks to make a trellis, quite convenient.
https://www.amzn.com/B0713PLVY2
Also I find the 7 to 10-gallon ones can fit nicely into milk crates. Just finished setting these up for my neighbor:
(It's purchased sand that they put there, maybe I should put some bricks underneath the milk crates just to be safe.)