I could do a link path analysis with various configurations using the radio mobile software (http://www.ve2dbe.com/index.html
) which would give you a fairly accurate estimate of the signal quality of the link. Otherwise I recommend getting as close as you can with this tool http://www.ubnt.com/airlink/
(I have found that the airlink tool is not very accurate but it gives you a decent quick look). The radio mobile software is great tool and it is worth learning but it is difficult to get started with. I have used and verified my setting on radio mobile with before and after prediction and results and found that I can get pretty close.
I have quite a bit of experience in determining the required equipment to make stable backhaul links. I will need the GPS location and height above ground level of each location as well as the frequency band that you are using. It would also be quite helpful if you could identify what you wan the link to be able to do as far as performance. Contact me via email at: josh (at) thinkboxi.com if your interested.