I understand that you would like to make PI ProcessBook available through Remote Desktop Services (RDS). You intend to use the PI Server nodes to function as RDS servers at the same time. Not sure how you would load balance between your primary and secondary PI Server node but I believe using the PI Server nodes as RDS servers at the same time is not a good idea for the following reasons:
1. Server applications are used to aggressively use resources. This is one reason we generally don't recommend running other server applications on PI Server hosts.
2. There might be a negative impact on availability e.g. in case of maintenance or unplanned downtimes. Again, I am unsure how you would achieve load balancing so it might be you've considered this topic already.
3. PI Server security is likely the major concern with the setup you plan, since RDS increases the risk to become a victim of a cyber attack.