There is no good substitute for a decent stand. Unlike bassoons, which can be stood on a low-rise Fox stand and still be stable, there is much more "weight" up high on a bass clarinet.
The "bassoon" style stands are expensive, but you are in effect paying for the stability that it offers. The peg goes in the cup or box at the bottom, the neck goes in the upper end, and gravity holds it in place.
There was (note the past tense there) another stand that worked pretty well with an extended range bass, that being the Anderson die cast alto/tenor/bass clarinet stand. Very compact (it folds up to fit in a "Crown Royal" bag), relatively stable (my Selmer 33 has never been in any other type, and it's kept my horn in good shape for many years), and adaptable (I combine mine with a wooden base that also holds my baritone, bassoon and two other sax stands along with clarinets and the like.
The firm is long out of business, but when they were making them they were quite inexpensive. I pick the occasional one up on eBay, but I've not seen one there for a year now.