Ouch having to move a tank just a few inches is a lot of work, I would agree. Depending on the size of the tank and the sand/rock load inside you will have a job on your hands-not to be a negative Nelllie here. As a general rule of thumb hobbyist have about one to two pounds of sand per gallon and at least that in live rock. Water weight is approximately 8.75 pounds per gallon (salt water). The tank depending on glass or plexiglass will have considerable weight. I am saying all of this as the more water you have inside the tank the more movement you will have that can create a leak as the waves hit the sides in the move; therefore remove as much water as is possible and if the tank is glass then there is a good possibility of cracking the glass bottom if rocks fall in the move as well.
Please take every precaution possible as a bit more work up front will be worth the move down the road.
Good luck.