Which is odd because last time I checked Jabba was only the head of his desaljik and he was in direct competition with another major clan on top of a whole bunch of other clans. This would make it improbable that he controlled most of Hutt space.
And I know it was his resort, but his only other locale was the desaljik palace on Nal Hutta. This is hardly proving the influenc of someone who is as you said second to Xizor.