Chris,
some pieces of advice:
1) don't change your name. You know what your skills are and are
willing to recognize that. That is a rare trait on this NG.

2) I've done lots of pieces before I ever got a jointer and, while I
wouldn't go back to being without a jointer and I have done better
pieces since I've gotten one, I am not convinced that a jointer is THE
essential piece of equipment for woodworking. (I would suggest a list
but then that would derail this thread).

3) You can safely rip a twisted piece on a TS if you mount the piece
to a sled and shim the piece so it can't move. I've done this with an
8 foot, 16 inch wide, 8/4 piece of curly cherry that had a 2 inch
twist in it. Frankly this is a PITA but worth it for the right piece
of wood. A piece of Yellow Poplar, IMO, is NOT the right piece of
wood. Replace it with a flat piece and use the piece you have for
jigs and crap.

4) many wood supply places will not only plane your pieces but usually
have a jointer too and will flatten the board as a service. Unless
you have a quick project that you wanted to get done long before this
thread ever ends I think a trip to a good wood supply store is worth
it because you will be able to get the wood you want and also learn
about your choices for future projects. This is something that will
quickly move you from *_The New Guy_* to yet another wood dork (YAWD).

TWS