In my opinion scales are approximately (inch):
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I once tried a cello as a bass, and admittedly that was a ply cello, but I was disappointed in the sound, and when we parted it was a normal cello again. As a cello it was a fair student instrument, and I was truly amazed how it sounded in the hands of the guy who tested it (with a DB bow!). Took him about 7 seconds to decide. But a cello is not a bass.
The problem with putting a DB sideways on your leg is that a DB is much deeper than a BG, and that, and the direction the strings run at, makes proper pizz technique more challenging (wrist bent at awkward angle). In my mind it's more a stage trick, particularly if you do it with a big one (43.3"), but proper playing is best done oriented upright. But that's just my opinion. I believe Mr. Fitzgerald has some videos on YouTube on right hand technique, have a look at those.