Thanks for your reply, which proved pretty prophetic. I actually bought a new Nikkor 300 F4 and TC 14E II a few days ago (from Adorama--free shipping UPS Ground 7-10--arrived NEXT DAY--although just a stone's throw away from New Jersey). Went out Wednesday to do the 300 hand-held, and yesterday with the 300, TC 1.4 and tripod. I was surprised that the hand-held worked so well, even at speeds below 1/500. And the weight was manageable: four straight hours of shooting without a break, and no muscle fatigue during or after. But the tripod results were superb, the best image-quality shots of my life, even on a day of medium overcast, and speeds as low as 1/160. As many had mentioned, AF is a bit slower when the TC is in use, but not as slow as I expected. Many reviewers had warned about the Nikon 300 tripod mount. But my Manfrotto/Bogen has a quick-release plate, and that platform is plenty sturdy, as NONE of my 140 shots suffered from camera-motion-fuzz.
I could not be happier with the above two lenses.
Best wishes on Texas shooting. Bird season in eastern Massachusetts peaks in April and May, with all of the migratory songbirds passing through, so I'm getting pretty revved up.