Currently out network is setup like this:
Office with 8 load balancing DSL lines NAT: 192.168.254.1
out to 5Ghz Link to 4 towers, 192.168.254.2 - 192.168.254.5
then each tower has 192.168.0.0/24, 192.168.1.0/24, etc…
with Routerboards setup as hotspots. again NAT’d
whats the best way so we dont NAT at the office, then again at the towers?
Just don’t nat at the towers. No need to. If you don’t feel like adding static routs, not that much with only the five RB, just set up RIP on all your Router Boards. RIP will sort routes automatically.
i guess im missing somthing.. What should the IPs be for the clients from the DHCP on the tower so we have good # of IPs available. more then /24 ?
Thousand apology’s, missed that one. 
Make use of class B subnet for clients. /22 will give you 1022 IP’s or if you want to use /24 in your pool add another pool for the next range and so forth. Assign one ip to your interface of RB for each pool, which of cause is not in the pool. In your case your router board will have a interface with four different ip’s on the same interface.