Multiple VPN Scenario - Can this be done?

I am getting ready to dive into the deep end with multi-site VPN, and I'm definitely finding out where my networking knowledge gaps are. A little help would be appreciated.

Proposed Topology:

1. Site A
   
   1. WAN A
      
      1. General purpose internet pipe
      2. VPN connection to AWS VPC
      3. Incoming Client VPN Connections (offloaded to OpenVPN server)
   2. WAN B
      1. VPN Connection to Site B
      2. VPN Connection to Site C
      3. VPN Connection to Site D

I presently have all of 1.1.x implimented, running on an EdgeRouter PoE.

I'd like to add all of 1.2 and I'm not sure what limitations I may run across. Mainly, I'm not sure if a single EdgeMax device can be configured to support all these VPNs.

I need the VPN connection to AWS as well as the VPN connections for the other three sites to be up all the time (4 total), and also allow for incoming OpenVPN connections to be passed through to the server for remote access. If something like an ER-8 can be configured in this way, that would be perfect for me.

Thoughts and pointers greatly appreciated!