I have landed PTs at both V bases and A bases, but they have always been friendly, not enemy ones. I've never tried an enemy one, but I will and post here when I get the results.
The way to land at V and A bases, ( at least what works for me):
A base: Go to the area nearest the end of a runway. As you approach, slow down. Slow down some more. You will hit bottom while still a ways from the shore. If you are going fast, instant death! But at 5 mph you will gently "beach" on the bottom. Then hit the tower button and you will land successfully.
You cannot land at a Town next to the A base, I tried.
You can also put it in reverse and back out to go fight again if you want.
V base; I just go as close to the base as possible, and do the same as above, nice gentle landing.
So far it's worked every time. The trick is learning from experience how far out to start slowing down. I have a "rule of thumb" that I'm testing, if it works consistently I'll post it too.