The idea is good. But like some mention you gotta respect the small clubs. So make the same rules like in Germany where
3 rd liga is the highest rank B team can reach, and they start at the buttom leagues of couse. But they can play DFB pokal
( like FA or Carling cup). Bayern Munchen A team once meat B team in the DFB pokal!. This will give some great boost instead
of reserve team matches with all due respect.
That's like cheating.