Watch craigslist and pick up a beat up old bar box for a couple hundred and lay it on the floor somewhere with the legs off. If it's too low shim with blocks of wood until it's perfect and raise it as he grows until he's tall enough to play on your table. If there isn't room push it against a wall. He won't care that he can't get all the way around it.
Then put the legs back on and put it back on CL and get all your money back. Ramps and stilts and crap around the table are not the answer. It's an accident waiting to happen.
JC
I like this idea the best.
I read a story about a martial artist whose father planted a small tree....
...and taught him to jump it.
As the tree grew each year, so did the child...and he kept jumping it.