To make long cuts I use a straight edge or my KREG Rip Cut
When I needed to make straight cross cuts I decided to use a home made jig.
This jig has the crossbar extended to the left to provide clamping space. My jig is 16 inches long, making it longer than typical commercial cross cut jigs or speed squares and more manageable than 48 inch straight edge. A jig like this is also much quicker to set up and use than a straight edge that has to be aligned and clamped at both ends.
I haven't painted the jig red yet, but I will. Since I have two circular saws I decided to identify the saw and blade that match this jig. This way the correct jig/saw pair will end up at a work site together.