Inq has already made a tiletset with every tileset in it, so...yes. :D As long as it's the right width, it can be as long as you want. However, it'll make your game really laggy, so you'd probably want to only add tilesets that you really want to work together, and make a few of those (like, say, grassland/woods/forest, or forest/swamp). If you have some spare time, it might just be better to comp in what items you specifically want. That way, you can make a comprehensive tileset that's relatively small.