I level up vs AI until I feel confident enough to go into PvP, it really is the best solution and when you think about it we are lucky to have that option.
In most other level + gear based games you wouldn't be able to take your level 10 gear 5 guy into a fight with level 100's with gear 108. They have level brackets as standard and you simply wouldn't find yourself in these unfair situations. For Honor doesn't do that for you, so think of AI mode as you doing it for yourself.
The matchmaking is a joke in this game, almost on par with networking. And I think it's because if you observe how the sequence goes, you will see that first it looks for the same ranks and stuff and then it moves all the way to extended to all skills and levels. There is something wrong in their algorithm for sure for it always chooses the widest panel of possibilities before locking to anything.
Anyway, back to the real subject, as long as Ubisoft doesn't fix matchmaking, there is no real good solution to your problem I am afraid. Play other games and wait a bit in hoping they will come up with some good fix. Personally, I always use my main to go pvp so I can farm good gear and steel for my next hero: the centurion. And so I usually get matched with low levels and I feel sorry for them.