I'm gonna go out on a limb and here and say BAD IDEA.
Savs can be just as horrible a beginner monitor. They still reach lengths of 4-5 feet and require a only a slightly smaller enclosure than a water. They are imported by the millions yearly, and less than 1% make it to a healthy adulthood. Not to say a savannah can't make a decent pet with a lot of work, but it's not a good idea. I've had bad experiences with keeping them myself, and it was'nt all its cracked up to be.
By the way, if you ever come across 'kaffir2' aka 'danceswithsavs' on the internet, stay away!
But anyway, good luck with the bearded/water dragon!