"Had been a fleet of relatively large tankers available to move oil from the Venezuela fields (brought into production in 1922) to Californian ports (and thus fill demand relatively cheaply), would those Texans still have invested in such wildcat drilling?"

Probably, because you still had to build and run the tankers, which would not necessarily been cheaper than shipping the oil by rail  - the usual method before Big Mistake 2.  Another thing is whether the ports in Venezuela of the time could have handled large tankers - the tankers used in the Curacao run were specially built with shallow drafts, which led to problems replacing the ones that got sunk by U-Boats during WW2.

The late David Brown pointed out that another thing about the drop in naval construction during the interwar period were the subcontractors that manufactured the various components shrank as much, if not more, than the shipyards handling naval construction.  Much of those contractors could not have been repurposed for producing components for, say, tanker, and still be much use for naval construction.