Yeesun Flag Pole,6FT Flagpole Kit for 3’ x 5’ American Flag-360° Tangle Resistant Technology,Stainless Steel Professional Outdoor Flag Pole for House Truck & Boat Use (Without Bracket,Black)

Q: Can this be used for a flag car mount?

These are probably the best flag poles I've purchased for my home. They come in sections and screw together. Don't think I would use them for mounting on a car unless you plan on keeping the speed low and the flag small.

Q: If I buy another pole to extend the pole to about 8', will that work?

Depends of what you're planning to do, if it's gonna go in the back of your truck it'll bend and break if you go above 40mph. I found the only way to use it and have it for a long time is to take a section off and place it right behind the cab and in the center, gotta drill holes and secure it with bolts. The cab and the lower height will protect it from the wind resistance. Hope that helps