Man, I feel stupid....cross-cutting question.

[keakap]

...
I can definitely see the need for a longer gauge extension, so I will probably build one today so I can get to work the correct way. The sled idea sounds intriguing, too, so I may investigate that....

SLED:
IIRC, you have 2 ShopSmiths? Do that mean you have 2 miter gauges?

If so you almost have a Sled awready.
Put one in each slot, attach an auxiliary fence- taller than the workpiece- to them both. The length of the aux fence can be as long as the workpiece if you want. When the Aux fence is "Firmly" attached to the gauges they will Auto-Square the rig.
Let-er-rip.
That is to say, Crosscut.

[keakap]

SLED:...an auxiliary fence- taller than the workpiece- to them both. ....

An upgrade to the "Cheap man's- I mean really really cheap- crosscut sled":
(assuming you don't need support to the left of the blade):
# first time the rig runs thru the blade, make the cut completely thru the Aux fence. That's your "cut Line".
# acquire a FastCap "Old Standby Flatback" tape (chea-- uh, inexpensive)];
# take your square and set it on the WP with the blade positioned exactly on the cut-mark (which if you want to do this with max accuracy and/or in the dark will be a knife or scribe line, not pencil);
# then holding the square firmly to the WP slide both to the right until the square's blade just makes contact with the Aux fence end.

# while holding the WP (w/ hand or clamp) firmly in place, remove the square and tape;
#cut.

{other details like supprting the cutoff and such are not unique and are left out}

This method is extremely accurate, eliminates paralax problems, and, if you don't re-read these steps with each cut, is Fast once yer used to it. {I used it for all the 2x4s for my workbench- 53" to 16"- and could not read any error without magnification.}

[hope i got all of it right]

As mentioned, Max accuracy attained with knife used to make cut-marks instead of pencil. Almost always is anaway.

[JPG]

Having a workpiece simultaneously contacting a miter gauge
(with or without an extension or sled) and the rip fence and the blade is a NO NO regardless of the relative positioning of all of the above!!!!!

[keakap]

Having a workpiece simultaneously contacting a miter gauge
(with or without an extension or sled) and the rip fence and the blade is a NO NO regardless of the relative positioning of all of the above!!!!!

Not necessarily, in the case of a sled.