I made a simple 4 legged table that just sits on top of the lathe stand and over the bed and about 3/4" below the center line. Nothing fancy, I just lift it out of the way when I am not using it. When the need arises nto do exact sanding I will make a miter slot. Untill then, I just free hand mostly curved stuff. I generally keep my jigs simple and complicate them if I have to.
BTW, the motor mounts under the lathe bed rails. Changing speed ranges is a piece of cake. Probably 10 to 15 seconds. The speed ranges overlap each other. I normally use the sander at around 2200 to 2400RPM. No particular reason other than it 'feels right' to me.
If I remember, I will take pics later on today,
There are several other folks on here that have the same lathe.
I dont know what the combined weight of the lathe and the cart but it is very stable. I bought four 3" locking wheels with brakes from Home Depot for around $50. Theyb are worth it.