Ok I also think this is the only line that can give a clear win. Ideas of Bf4 to trap the knight on f1 seems too slow and will allow black pieces to activate the rook... So:

1.Rxh5, gxh5
2.Bh6, Nf1
3.c5 dxc5
4.bxc5 and black cannot stop d6 d7 d8

3... Ng3
4.c6 bxc6
5.dxc6 Nxf5
6.b5 and now the a pawn will become the hero

Edit: I just noticed black can do Nxh6 and Kg7 to stop the pawn. Maybe we should keep e4 somewhere hehe