BACKPACKING TENTS always involve compromises between weight and space, especially with solo ones. How small a tent can be whilst still being functional is, to some extent, a matter of what you’re prepared to put up with. There are tiny ultralight tents with barely room to do more than lie down.
For me these are just about acceptable for overnight trips in good weather; but for anything longer I prefer larger ones in which I can sit up, store gear and cook undercover. Will you live in your tent or just use it for sleeping?