Good for you for educating your self about permaculture.
If you plan on teaching
PDC courses, You will have to get your certificate at the least, otherwise you
should not advertise your course as a
PDC.
It is possible to make a living, So far, everyone I am aware of that does so uses multiple income streams. Example; they have a permaculture farm, they teach courses on their farm and they
sell the produce from their farm.
Just having permaculture knowledge can be enough but you might find it to your advantage to have some knowledge about biology, botany, as well as the chemistry of soil, mycology would also be good.
Designing is only a small part of permaculture, it also requires you to know about soil, plants, animals, and ecology. Just about anyone can sit down and draw out what they think is a good design for a farm or gardens.
A permaculture designer also includes,
water flow (collection, distribution and storage), work flow (plantings are laid out so you are moving from one space to the next closest space with a conservation of effort), plants (what will grow best where so you get maximum output for the effort put in) and these are just the basics.
Being self taught is not really a set back but being in practice, so you can show how what you teach works is what makes it viable and believable to anyone who would pay you to teach them.
Don't forget that videos do sell, since that is your area of expertise, that could be a great way to start your business, making films of how permaculture works.