This is mine, its a strengthened creeper. I have had to swap the wheels on it, but its done a dozen swaps.
I have managed MR2 engines in / out on my own, I even got the 1UZ out all on my jack, but you shouldn't do it, its dangerous. It's a lot like going out with a fat bird; you need a mate to rescue you if things go wrong. Big heavy things hurt when they land on you.
Chris.