Basically what I did is steal the design from this:
I found the cheapest metal sprayer on the internet I could (I think it was about $40). Took off the sprayer attachment, found the right size tubing (clear plastic is what I used) that would fit over the nipple on the tank, clamped it with a simple small hose clamp (the kind that tightens down with screwdriver)
then attached a nozzle to the other end with another hoze clamp. You can get solar shower type sprays at REI for a couple of dollars.
Fill partially or fully with water. Set in the sun for a while (I painted mine black this year, haven't tried it out yet), then put on your stove if you want hotter (I do!) don't forget to take out the plastic pump up part before heating. heat to desired temperature, pump up, turn on the shower and you have hot water. I have an old hot tub thermometer that i use to monitor the temperature when I heat it. I think I have a picture somewhere, I will try to find or take another. I don't take of the hose when I heat it, just make sure it is coiled up out of the way on top when heating. but do take of the pump up part.