BountyHunter,

Well, I don't remember ever seeing it by that name. I have a copy that dates from the '60s, and it's still in print as "Tunnel" (although with a spectacularly stupid cover illustration):

Amazon link

I remember Rod's lesson from his sister well, I even have it stored in my Palm, along with some of Deacon Matson's advice.

I know what you mean about some of the later writing. Heinlein went through some very distinct "periods" in his work, and some of it was just bad, sorry to say. People who get exposed to that writing first tend to dismiss him entirely. Without going into detail, there were apparently health reasons for the changes, and there are exceptions. Within "Time Enough for Love", aside from the immortal "Notebooks of Lazarus Long" that get quoted every day, there is "Dora's Song", which is a fascinating and fairly detailed study of pioneering and wilderness survival. And, of course, there's "Farnham's Freehold". Even such little-recognized writings as "Farmer in the Sky", "Red Planet" and "Coventry" had strong survival themes.