RVDA/RVIA certification is probably the patch you want on your sleeve.
It looks like you can accomplish most of it online if you're proficient enough in those areas.
Any courses should be tied to that organization and they may have a list of accredited courses and learning centers.
If you don't have any experience in the field, a job at a dealership would be a good starting point. Hopefully, one of the guys that work in the field will post and let you know how important/unimportant certification is to finding and holding a job as a technician.
I have a few certifications and license in some industries. Some of them are essential for employment or self employment and a couple are not that much. Most of my certification is expired as the organizing body wants continual fees to remain certified.
Good luck with your career and I would think a good RV tech is an in-demand occupation at this time. I base that assumption on the recent increases in sales.