Sorry for late response - glad to hear I’m not the only one thinking about it (apologies for not finding the previous requests).
I suppose “Alt+F+number” is one solution if “Remember open files” is checked, though I find that setting slightly annoying for two reasons:
having all my PDFs open to the last place (say page 24) if I’m opening up the file for the first time in a while is generally not what I want, and
having all of my tabs reopen next time Sumatra is launched (i.e., if I close a window with ten tabs because I’m done with the project, it’s slightly annoying to close all ten to start fresh. Additionally, if you access files on a networked drive, and later open up the program when you no longer have access to it [work v. home], then the program has to freeze and try to access to disconnected drive before giving up, which takes time).
Because of those quirks, I disable “Remember open files”. Maybe if those two functions (remembering recently opened files in the File menu, and remembering open tabs/location) were separated, then the Alt+F+# would be a more workable solution.
Obviously, this is just a minor issue. Just my 2¢.