I climb, safety in, then haul equipment and tools. Having someone on the ground who can control a tag line and act as a second set of eyes is highly recommended. Using a haul rope and tag line allows you and the person on the ground to raise and lower equipment without getting tangled in the tower.
My career in telcom included some tower work including training in high angle rescue. I don't think you need to invest in a
Class III rescue harness, but a
basic sport harness, related accessories and training in their safe use is worth the money IMO. You also need to be able to inspect the tower and determine with certainty that it's safe to climb and support the loads you'll put on it with ropes and equipment.
At the risk of being accused of fear mongering, I know of real incidents where falling from even six feet has resulted in death.