I'll second the short (standard) fence. Long supports are necessary but not long fences. Once the board has cleared the blade you really don't want or need the fence to influence the cut anymore, whether the board is straight or not. In the US, table saw fences extend past the blade maybe a foot. I've read that in the UK, this is considered too far for safety sake and that their fences are even shorter.
Also, it's often better to nibble strips off one edge of a large chunk of wood, even if it's heavy. Ripping a 2x12 down the middle can release stress in the board too quickly and you might get some major bowing or pinching.
Ian

: Unfortunately, I'm going to play the devil's advocate a bit here.

: A long fence is good if the wood is straight. If you have a bend or
: hollow in the wood, a long fence will give you an uneven
: thickness of strip. I have found that a shorter fence works best
: for me. I intentionally fasten a board along my fence up to the
: blade. So after the strip is cut, it now travels free. I use
: three feather boards. Once pressing the board down solid on the
: table top - just before the blade. One pressing in - in front of
: the blade and one further forward keeping the board parallel to
: the fence. After each strip is cut, I put the board back into
: position and push my two feather boards in a bit and re-clamp
: them.

: I first sight down my board and If I have any bow in the wood, I
: make sure the bend is curved away from the fence. that way it
: will travel in towards the blade and the thickness will be good.
: If you have any bow in the wood facing inward towards the fence,
: you will get uneven thickness. (a thin spot) Some people
: actually snap a string line to check the lumber and hand plane a
: straight starting edge. This is one of the main considerations
: for getting perfect thickness throughout the run. I too have
: ruined some good wood before I noticed thin areas on my strips
: and the shorter fence cured it for me and more strict attention
: to the starting edge on the wood. And I usually rip 16' or 18'
: lumber.

: I'm sharing what I do and some undoubtedly like long fences and
: have good luck. But check that edge on your wood before you�
: start.