I wouldn't even take the fish out if it's that small of a fish tank, empty it down to about 2-3 inches of water, just enough to cover the fish without laying them down, then carry it CAREFULLY to the tank's new location, and stick it where it goes, then fill'er up.
On small tanks, don't overthink it. I moved an old glass 40L with some water and substrate several miles from an old house to a new house, up and down steps and never had a single hiccup. Then just recently I helped a buddy move 10G and 8G tanks half full from one apartment building to another, across town, with the fish still inside.
The key? Just keep things level, take everything slow, have a buddy there to help you if you need it.