" long board off to one side can cause problems from the drag" Cut pieces few inches over length B4 beveling.
Wax table top, miter slot, and blade so all that slides EZ. Good stiff miter extension or sled with the sandpaper on it as thing mentioned, paper on top of sled as well, so those parts don't slide. Make sure miter or sled is square to blade.
Wide set blade may help, rough sides of blade make wood want to dive at front of blade, climb at back causing board to slide towards or away from blade. Hold board flat and against sand paper, or kwick clamps on sled.
"I always seem to have this problem when trying to vut 45's on
my tablesaw." How about on others? Maybe your not holding your mouth right. When was last time saw was tuned?
"when trying to vut on tablesaw" Do not vut on your saw or anyone elses, vutting on a saw is illegal in 17 states, most of them in the Bible Belt.
thing, is that you're incra miter? How do you like it? I used incra jig on router table for a long time a long time ago. Mostly for dovetails.
It was way accurate as long as bit was sharp and didn't have to lug heavy router through slots of other style dove tail jigs. But that Inca miter always looked flimsy to me.