This is VERY doable!! I have done it.
Just get one or two or as many as you need plastic tubs from target or walmart. Put everything into them including water with a heater and some flow to keep them alive. They'll do just fine without light for a couple or three days.
Then empty the tank and cc. Get it all clean and add your sand. Start adding water... it's ok to add some new water. Just think of it as a big water change. If you have a LFS, they may have some water for sale that is a little more aged (that's what I did). Then add everything back into the tank. Now you have a brand new sand bed and everything will be fine! As long as your LR is cycled and mature, you will not have a re cycle. I swear by it. I have done it twice without a re cycle.