This is all relative to the OP's statement that....

• OP hates getting flats on the road. (not sure where else one would get a flat that they like!)
• OP can't run wider tires on the current bike.

Though the OP might not even be asking about what to do for flats.

If the question is just about wider tires, that can't be used on the current bike, then to what purpose is that? For the average person that isn't competing with others or themselves, the width of the tire is only about comfort. They aren't necessarily significantly faster or slower than any other width tire.

And a easy rolling tire of a narrower width can be more comfortable than a hard rolling tire of a wide width. However in the same easy rolling tire, the wider the more comfortable. And not necessarily faster or slower.

Since the OP can't put wider tires on the current bike, then tubeless easy rolling tires in whatever width fits the bike will probably will take care of the risk of flats and make the ride much more comfortable.