There's more that one way to do this, but it's doable with one burner. I use a 10 gal cooler (often on sale at home depot) as a HLT. I heat the sparge water in the brewpot during the mash, after it reaches temp transfer to the cooler. Then drain into the brewpot and sparge from the cooler.
I know I wouldn't want to carry 5 gallons of hot water to the garage, but that's just me.