As we know the ideal situation would be an airfoil that could respond with the largest possible lift force and with the least necessary amount of resistive factors such as drag.
In any wing structure design, the primary factor that governs is the so-called Bernoulli's equation. I won't be very mathematical here but basically it says that if the velocity of air is increased over a certain point of an airfoil, the pressure of the air is decreased. In order for that to happen, the various pressure points in the wings must be distributed along its surface, and the larger the area the wider the spread thus more lift generated. The drawback though is that for that to happen, the so called "thickness ratio" you referred to must be accordingly increased to support the force parameters. That will always be a factor present in any airfoil design. In my opinion, I guess the only way to override this would be the production of innovative composite materials that have the adequate strength to support the external parameters of the airfoil and at the same time produce an elevated lift-to-drag ratio. It all really depends on the core material (multicellular structures) that is adequate for this kind of situation. Plus there is also the evil of infeasability over such projects.
One of the things I first learned in my first years at school was that behind every engineering innovation there is something that can still be improved and lead us to continue to think, so that further advances are made. It is nothing but an infinite loop. Anyway, enough of the philosophy....
PS: Thanks for your kind thoughts Buff. I appreciate it. I try and contribute to the best of my understanding.
Cheers and regards,