Paul Sellers has a few videos on youtube, worth checking out, on how to flatten a warped board with a hand plane. If you use his technique, then you should get your top together - relatively easy. (RL has the right idea... Listen to him. He generally gives very helpful advice.) I use hand tools on my MFT. Yes, it's not very fun, because the table shakes quite a bit. If I put the table up against the wall and plane in the direction of the wall, i find that it helps steady the bench enough to get something done. Also, I use that spongy drawer liner, from the hardware store, to help grip the piece.