I have one of my subs elevated to 4 feet to effectively reduce a height induced bass null and it's works very well. Mine is fwd firing however.
How many subs do you have? Do you have an acoustical measurement tool to see what your ears are hearing?
If you have only one sub then you will get more room gain by placing it on the floor next to a wall or corner. If room gain isn't an issue then I suspect the table location will work but tools to measure it are kinda important.