Actually, I have now enabled the search indexes for the following prefix+suffix combinations: 4+1, 3+2, 3+1, 2+1, 2+2, 1+1, 1+2, 1+3, 2+3, 1+4. I may add longer combinations later, but for now they will be shortened and filtered, e.g. 5+3 will use cached 4+1 and then filter the results in the browser with JavaScript.