rdweb, terminalserver, domain for multiple customers

Hi, i will setup a terminalserver/rdweb enviroment for multiple customers. Is this a ok way to do it?

DMZ

rd web access and rd gateway server



LAN

Domain: domain.local
server1:
name: RDDC1.domain.local
Role: Active directory, DNS

server2:
name: RDCB1.domain.local
Role: RD Connection Broker

Server3:
name: RDLS1.domain.local
Role: RD Licensing server


Child domain: cust1
Server3:
name: RDDC2.cust1.domain.local
Role: Active directory, DNS

Server4:
name: RDSH2.cust1.domain.local
Role: RD Session Host Server


Child domain: cust2
Server5:
name: RDDC3.cust2.domain.local
Role: Active Directory, DNS

Server6:
name: RDSH3.cust2.domain.local
Role: RD Session Host Server


This way each customer could have there own domain controller/server and there own terminalserver/rdweb server. And all users could use the same address to get to there terminalserver, https://rdweb.domain.local/rdweb
I need each customer to have there own domain controller/server since thay have some program that need that, they also need there own terminalserver.

Should i use child domain or tree domain? Is it possible to do it with tree domain and get one rd web access, rd gateway and connection broker server to function for all users/customers?