I've never made 2x T&G, so take my advice for what it's worth! I think you're asking a lot from your router, as well as your time to make T&G for a whole cabin; that's a lot of material you're hogging out. Instead, I'd recommend using a table saw and a dado set to make both the tongues and grooves. Also, rather than making all those tongues, consider using splines in grooves. Also, if all you need is decent alignment of your boards, do I dare suggest using a biscuit joiner? Good luck!