I consider myself a rationalist and have an epistemic view of rationalism, but these three claims about what I am "required" to believe are bogus:

"(1) a privileging of reason and intuition over sensation and experience"; sensation and experience are primary, you may doubt them if they conflict too strongly with your reason and other sensation and experience, and look for more evidence either way, but without sensation and experience you have nothing to reason about.

"(2) regarding all or most ideas as innate rather than adventitious"; I have serious doubts that "innate ideas" even exist, except, possibly, for some evolutionarily programmed "ideas" (depending on how you define ideas).

"(3) an emphasis on certain rather than merely probable knowledge as the goal of enquiry"; how can a person emphasize certain knowledge over "merely probable" knowledge when all knowledge is to some extent probabalistic?

For coming up with better ideas, the next best thing to actually testing them, and many cannot be practically tested, is coming up with lots of different ideas so they can be easily compared.

This reminded me of another rationalist novel, Hal Clement's "Half Life". A future where most of the dwindling population is working frantically to find a cure for the proliferating diseases that are driving humanity towards extinction. There are several rules about how to present ideas to avoid premature evalution, one of them is - if you present a hypothesis you must also either include a way of testing it or include a second independent explanation.