Circular saw with a guide is what I usually do. Depending on what the material is I also sometimes score the cut line with a sharp edge to prevent tearout.
Lee, seems like the perfect excuse to build a table saw sled (or two). Sleds are an extremely useful "tool" to enhance the capability of your TS to accurately (and safely) cut boards to length. I have three sleds of varying widths and all are used to some degree - the smaller two sizes the most. Otherwise, what Jack suggested works. Masking/painters tape can be also used to minimize tearout. Jim
For a panel that size I'd be OK with the sliding table on my Robland although I'd probably have to move it over a foot or so to clear the clutter that invariably gathers on my workbench. Getting much longer I'd probably lean toward a straight-edge and a fine-tooth blade on my little cordless DeWalt saw.
For panels that size I turn to my Dubby crosscut sled for my tablesaw. The Dubby is a commercially available fixture for cross cuts on the tablesaw. Short of that, many have made their own shop made crosscut sleds that work once adjusted for square cuts.
The Dubby is nice because it will also adjust to cut a range of angled cuts by swinging its arm to the desired angle. It also has an adjustable arm you can extend from the end of the fence to set it for repeat cuts.
If you do any amount of furniture and cabinetry work where solid or plywood panels are involved, some type of cutoff sled is a necessity.
This is the best way that I found also, with a good finish blade. I've also used sleds, depending on the size of the panels. I just found the circular saw to have more control.
New sled it is then. I have a sled that allows me to cut 16” across, but it’s time to build a wider one.
I was always a little concerned that a wider sled would not work well as too much of the sled would not be engaged into the mitre slots when beginning the cross cut??
This sled works so well that I don't have any smaller size. Note that I extended the runners a few inches past back edge. This extension helps engage the runners in slots when installing the sled.
Material is 1/2" Baltic birch and oak runners oriented to minimize expansion across width.
Install runners in slots. Add some spots of glue. Place plywood on top. When glue sets remove and add screws.
I located the fence using a compass(trammel) to construct a line(fence) perpendicular to an established line(the saw kerf) as you will remember from geometry class.
Lee, starting a cut with a wide sled can be a little awkward with much of the sled hanging off the front of the saw, especially with a heavy workpiece. I solved this problem by placing a roller stand in front of the saw for the sled to rest on at the beginning of the cut. There should be plenty of the runners engaged in the miter slots to keep the sled straight at the beginning of the cut as long as you push the sled straight. The roller stand helps.
P.S. Bill's idea of extending the runners at the back of the sled should help keep the sled straight at the start too.
Good decision Lee. I have 12, 17, and 26 inch sleds. The 26-inch sled was a godsend for kitchen cabinet construction, while the small 12-incher is used all the time for most of the stuff I do. I sometimes use the 17-incher even for planks less than 12 inches if I need more support lengthwise and even then I stick a piece of plywood (1/2-inch corresponding to the thickness of my sled) under the end of the plank.
Yes, handling the largest sled can be somewhat awkward. Like Hank said, a roller stand works well and is also useful for jointing/ripping long boards. As I'm sure you know, provide some sort of protection at the rear of the sled where the blade might exit and cause a real nasty surprise .
I've done similar. What about just attaching a straight board to the top of the panel that overhangs the panel edge to be cut and not using an L fence? I think that's what I have done before. Guess it depends on how much you are removing. I think I roughed it with a jig saw and then just trimmed the panel on the TS to get a nice straight and square cut.
Anyway, just thinking out loud and trying to remember what the heck I did!