You are correct, the fixture itself is like 35 inches, but the legs can extend at least 2 inches each. so it wasn't an issue getting it on the tank. but the legs themselves attach perfectly to the rim of the tank.
Thanks for confirming! I knew the legs were extendable to a degree, but I was more unsure if the detachable(?) inner leg "flap" would fit over the rim itself so that you can use the screws.