You are likely dead on with your assessment. NEVER give a dealer any information. If they ask what you are looking at, just let them know "other brands." And if you want to do your homework, find out who owns these dealerships you are working with. Even if different, they are a long-term family network (literally) brotherhood going on.
This is why I am a huge fan of just dealing with dealers via emails. And do NOT let them know you are shopping out of region. Even when out of your local sphere of dealers, don't let others know you are from out-of-state, etc... if possible.
Remember: When is a dealer lying? When their lips are moving. ; )
Sorry to be so harsh on dealers, but their sole goal is to extract every dime out of your pocket as possible, nothing less, and help you feel like you got a great deal leaving the lot. I've never talked to anyone who thought they were screwed. Everyone I know says "I got a great deal!"...
Looking at this thread, it appears GT's are going for about $3k off sticker (close anyway). Not bad for a brand new rig. It will be quite fun seeing and exposing how much people are paying as move forward through 2018!