In my opinion, the issue comes down to where you store the camper, not how or where you use the camper (full-time excepted). I do an annual inspection of the seams and re-seal my camper as needed. I don't worry about it if I drive or camp in the rain. The camper lives in a heated shop when not in use.
And that is where I would worry about this 2002 Lance.... How has it been stored? Has it sat in the weather for the past 16 years? That's what causes the seals to dry out and start to leak. Or has it been well maintained and properly stored? If so, I wouldn't worry about the front window.
In regard to sleeping under a cold window... My 2003 Lance has double pane glass in the front window. I don't feel any chill coming off it. And I do like being able to look out it. I feel really closed in when DW pulls the blinds down.
HTH,
-Eric