[GraemeJ]

schnautza:

The simple fact is that a tripod base is the most stable and that is why most music stands, mic stands, etc., have one.

Quite honestly, I'm not really sure what you are asking for, or expecting to find. There is a whole host of tablet holders and stands on the market, unfortunately many of them are not suitable for 13"+ tablets. I had the same problem, but decided that I would continue to use my existing music stand. I reckoned to have saved more than enough space/weight by getting rid of all the paper charts to not have to worry about shrinking the stand as well - expecially as the purpose-built units seem to sell at a high premium.