Maybe this is an obvious question but...how do you do that if you ssh into your remote machines through a bastion that normalizes everyone to the same end user?

Maybe this is an obvious question but...how do you do that if you ssh into your remote machines through a bastion that normalizes everyone to the same end user? I'm unable to set a custom .bashrc on the remote server, because its a shared user, so how would you change the ps1 on the remote box?