I have a friend who has a Rohn self-supporting antenna tower (like the one pictured) with a directional cellular antenna at the top. The tower is probably 40 feet high and was erected by a previous homeowner. They would like to make it useable again but the antenna needs to be turned to point at a specific cell tower.
The manufacturers documentation indicates that the tower is climbable but I've never dealt with these towers and thats outside my expertise. Who would I even call for that type of job?
I've seen one of these be installed, also 40 ft tall, for fixed wireless internet. Once it was up right and ready, a guy climbed up and installed the dish.
He had a basic climbers harness around his waist and legs, and attached to that, 2 more strands of harness on his left and right, with a large carabiner clip on the end of each. He'd unhook then rehook the carabiners one by one, then climb higher. When he was at the top he used both of them to kind of give himself a makeshift seat he could lean back into, freeing up both his hands.
I've done my share of climbing, this is the (safe) way to climb. (Assuming the structure you are climbing is okay to climb) I myself prefer a full harness.