I've watched a guy in our one ride group that will rotate his crank, then while standing over the top tube lean the bike way over to that same side he moved the crank up so it doesn't hit the ground. Then he steps over/out. Lowers the top tube or step over by however long your arms can dangle the bike down at an angle.
Not sure what kind of bike you own, but if you own a bike with a round seat tube you could buy a dropper seat post like the MTB folks use. Then when you want to get off lower it down all the way.