Leeching my own characters?

This might be a bit convoluted but please bear with me.

I have three characters at the moment:
a level 46 Page
a level 45 Gunslinger
and a level 54 Cleric

I started with the Page and Gunslinger because I sort of like an underdog. But my Cleric was so much faster at grinding that it seemed much more efficient to get my Page and Gunslinger to leech off my Cleric. I figured maybe I could do this all the way up to 4th job but while they all hit level 30 at roughly the same time, they have been drifting apart ever since.

I'm not sure what the exp leeching calculations are but I suspect that I'm starting to get penalized for the gap in levels.

While I wouldn't mind using my Cleric as my main character, I'm not fond of the idea of grinding a Page or Gunslinger up to 4th job on their own grinding ability.

Is there a reasonable way to make this work without sacrificing exp on my Cleric? Would it work if I only leech one character? Would the benefit of having a high level Bishop be enough to make grinding my Page or Gunslinger up easy?

And perhaps most importantly, how would you guys go about leveling up a character like a Page or Gunslinger without relying on their poor grinding abilities?

Thanks

 

Thank you very much!