Daniel, if you want to work as a rigger, then you need to dig out those physics books, start working on vector analysis, and make sure you know your basic electrical principles. Modern day rigging, even on tent shows is a complex and challenging field.
I've been a rigger since the early 70's, even while performing, I always designed, hung, and maitained my own equipment. In the mid 80's, I slowed down performing and concentrated on technical work until by 1989, was completely performance free except for the rare special event or training session for stunts I designed. Even today, I still have to read, learn, and study to keep up with the technology, standards, codes, and legalities of what I do.
The riggers on shows are the first ones in and the last ones out. Throw working the show in there and you get some brutal days. Even with the high tech style tents of today with all their winches and hoists, the work is hard and the hours long. I think the only people who work harder are the animal handlers for elephants, cats, and horses -- thats a true 24 / 7 job. I know because I did that too.
It takes a long time to gain the respect and trust of the performers and show management that it takes to be a rigger for the show. It takes a lot of effort to develop the confidence to know that the decisions you make involve the lives and safety of other people as well as thousands and thousands of dollars of equipment.
If you want to work a tent show, get a commercial driver's license as well. It is a selling point for you if you can legally drive a semi over the road.
Hope this helps.
Warren