What is the safest way to run SSIS on Multiple Named SQL Server Instances?
I dont see anything wrong in your setup. To be fair, this is the correct way of setting up SSIS in a clustered environment.

Read up SSIS and clustering: What you should do instead

Also for the login failure, its worth to check  the Windows Server 2008 R2's firewall rules  to allow an inbound rule for either the msdtssrvr.exe executable or the DCOM port SSIS listens on.