I have done it. It's very nerve wracking while you are in the process but worth the effort.
1. Transfer as much water as you can from the old tank into storage containers to fill the new tank once in place. The amount you think you are going to need to finish filling the new tank..... double it. Haha
2. Transfer all live rock of course
3. Once you have all that out its pretty easy to catch your livestock. I put them into a storage container with some of the tank water and a heater while I got the scape setup and all the equipment moved and re configured
4. I didn't want to waste time cleaning the sand during the process so I went bare bottom in the new tank and put new sand in at a later date. Actually about 6 months later because I didn't like the bare bottom after trying it. I ended up getting rid of my old sand because I didn't think I would go back so had to buy new
5. After the new tank is setup and running and the temp is back up put your livestock back in.
This was my process and it went very well. fish adapted very well to the new tank almost immediately