Newer tanks have to have everything removed. They are made to be structurally sound in a static position when filled. Just put some water in a bucket & add fish. Put gravel & filter media in another bucket, make sure to keep it wet, or your bacteria will die. If you can save half the water that will help, I do 75% water changes on tanks regularly without problems.
If you move the tank with water, or gravel, you are putting stress on it that it wasn't made to handle. Future seam leaks or blowing out the side or bottom are a possibility. Makes a big mess.
Tolak