Is it SHayach to take 3 kids (including a 5 week old) on a road trip on a RV through Glacier YS and Teton?
While it could be a very nice trip, here is what my concerns would be.
1. How would you deal with a 5 week old in an RV for 2 weeks?
2. How would you carry the baby through pathways, walkways etc. (Forget about hiking )
3. Depending on how old the other kids are, would they enjoy a restricted trip because of the babies limitations?
How much time would I need?
I did Yellowstone in 3 days (2 nights ) Grand Teton in a day and a half. Could have spent one more day that was enough for me. ( I had an eight month old ). But a week would definitely be enough since your not really hiking.
Is it too late to plan for a trip in 2 weeks?
No
Since sleeping accommodations are taken care of (RV) there's nothing that really needs advance planning at all, 2 weeks should be ample time for planning.