When I decided to paint the masts of Great Ketch I knew that it needed to be done at my home. After I transported the masts - one at a time - to my home, I used the overhang behind the garage to suspend the masts, I then used a 10 x 10 foot tent to fasten a tarp over in order to keep the masts out of direct sun light.
One tarp that measured 6 x 30 feet was used to create a wall to protect the masts from wind - white tarp wall toward the right in the picture. The tricky part of painting masts outside yet under cover is one can not control environment. I wanted to have some ventilation so the ends were kept open and typically the breeze comes from the north end of the area to the south area.
My set up wasn't perfect but I was at home with all my tools such as air compressor, electric, water, restroom and fridge.
The picture on the left is displaying the main mast with all the old paint sanded off. The straps suspend the mast and allows me to rotate the mast to sand all areas. The base of the mast is in the foreground; toward the mast head is a blue tarp over a tent frame. When it was time to spray, I placed tarp on the floor from base to the head of the mast.