The recommendations you provided worked out fine. I was able to successfully pass both the UserID and userLevel session variables over to the other domain. And, I was able to access pages where SA access rules appeared to apply.
However, I noticed a side affect that I did not anticipate. After I had passed the user session over to the other domain, I noticed that the profile information of the user could not be seen, such as the user's first or last name, email address, etc. I can only conclude that passing just the UserID session variable does not necessarily mean I can access the user profile contact data. When I attempted to access the user profile.php page, the page displayed a message that it could not find a profile.
Is my understanding correct?