I'm understand that you don't want to get rid of RBF leeches, you need keep them inside as dummies for other players to beat, but it’s just simple not fair that afk dummies getting same reward as active player, not to mention they are ruining whole match by doing nothing.

RBF rewards should be higher, high enough to encourage players to do RBF more frequently. Lots of players tend to just do whatever content is rewarding, in spite of fun, because we are all so goal-focused and progression-minded.  

RBF can be very fun, even with trial characters. But the lack of rewards will not incentivize people to get in there, so the people who ARE in RBF are the people with 680+ GS and anyone with less comes in only to get smashed.  

If rewards were nicer, more trial characters would enter, and that would change the gear-demographic of the average player in RBF.   

Imagine if every RBF was full of people with trial gear and a little better; dramatically outnumbering the regular RBF rats who currently live in this gameplay mode? It's not cool to join RBF as a weak player today, because you are stepping into a realm of PvP gods. But it would be cool to join RBF as a weak player tomorrow, if the incentive structure had tilted the balance and caused the majority of people in RBF matches to be weaker players.   

More good fights for more people! Maybe rewards will help achieve this. 

With the new gear caps in node wars and sieges maybe they could implement something like that to some of the RBF channels to see if players enjoy it.  They already boost your AP+DP if you're below an unknown minimum requirement.  I bet after some testing PA could find the sweet spot on the gear caps.  Soon most players that complete a season will have full TET boss gear and capotia accessories+tuvala accessories, trial characters give you ~620gs.  Cap it around 630 to 640?  I know some classes struggle against other classes with similar gear score but hopefully the rework will fix some of those issues.  Make it about player skill and team work instead who's got the best gear.  Obviously, there will be other servers that do not have this cap where the players that have accomplished higher gear scores can put it to the test.

EDIT:  Sorry, I didn't even contribute to the main topic.  Yes, better rewards!  You could use RBF seals able to purchase certain boxes that give anything from black magic crystals, yellow accessories and boss gear.  For the life skillers have a separate box that can be purchased that awards life skill tools or parts.