In helping a harpist find a transport cover, I found out Four Seasons Harp Covers now offers a gig bench back pack in three sizes. You fold your gig bench, put it in the bag and carry it as a backpack. They have the measurements on the website so you can figure out if your gig bench will fit into the bag. www.harpcovers.com
I have a length of rope with ends tied together (as in a circle). I fold my bench, hook the rope over one end of the bench legs, and hook the other side of the rope over the top of the harp. I hang my harp bag over the other side of the top of the harp. No need to buy anything or wear a backpack…a piece of old clothesline does just fine.