I was thinking about it because I would REALLY like to try few classes in pvp,
or improve my PvP skill without hurting my team-mate rating.

Actually there is not any 4vs4 training mode,
and the 8vs8 is 99% of time a dead queue, that can make you wait even for content that will pop before than 4 hours,
so you dont' have any true space to pratice before to go deep in a 4vs4 match, that is totally different from a Frontline.

Option 1:
Add the 4vs4 training, my only fear is that will shatter the pvp queue even more.

Option 2:
Add a checkbox on Duty Finder Settings called "PvP Training".
If you check it, you will get no rank for a victory or a loss *, also your teammate won't lose any points in the case of a loss*.

*or maybe for a loss something like -3 -2 or -1 points, in order to prevent players only using this feature for sit in a high tier.

And maybe make the first 5 matches of a newcomer players queueable only in this way <3

What do you think about? Is it all bullshit? Have you any hint?
I hope this will help to make people trying different jobs, strategies reducing the usual pressure linked to rankings and make few new players less afraid from trying pvp.