Great idea about putting your shirt in their cage for them to cuddle up with, and also rubbing your scent on everything. I think that will make a big difference. I understand how worried you must be. I went through the same thing when I left for a 2 week vacation. I knew my little one was getting great care, but I was still nervous. When I returned, I quickly realized she didn't forget me at all and we basically picked up where we left off. The best thing you can do is what you're already doing right now: preparation! You're thinking ahead, arranging for good care and anticipating their needs. What helped me was trying to keep things as familiar and routine as possible...food,,schedule, pouches, toys, etc. And it's great that they have each other! I think it's wise to have them stay in their cage so they have that safety and security. Do you have an exercise wheel for them?
While I seriously doubt your gliders would actually forget you, they may feel a little unsure and/or moody when you return. But getting reacquainted should be a fairly smooth process, certainly quicker than the initial bonding process. As you know, time, patience, and love will go a long way to reestablish that trust and bond that you have worked so hard for. Wishing you all the best and a wonderful vacation!