Setting up an "N" repeater

RouterOS Wireless Networking
1

I’m quoting for a point to point “N” link that needs to go through a repeater.

The two buildings are about 600m from each other. The repeater is high up on a mountain 5.5km away. There is no line of site between the two buildings because of trees. There’s no chance of getting the trees chopped down. Both sites have good line of site of the repeater.

My plan is an RB433AH with a R5N and a dual polarised antenna at each client site.

What do I need for the centre?

Is it a RB433AH with 1 x R5N and 1 x dual polarised antenna, or is it a RB433AH with 2 x R5N and 2 x dual polarised antennas?

Thanks in advance.