You don’t need to be able to study the designer to know that one exists. Evidence for a designer’s existence is clearly observable and testable. The order and complexity that science itself depends on is evidence of design and can be tested.
Certainly scientists running a complex, controlled experiment expect it to show thought, reasoning, and intelligence. If order and complexity are not evidence of intelligence than all of the above reduces science meaninglessness. A *scientific* experiment then means nothing more than chaos.
I suppose one could consider the fact that oxygen will bind with hydrogen and not helium shows intelligence on the part of oxygen.