I Am Confusion

Last night (this morning?), I finished reading I Am Legend. Well, re-reading would be more of an accurate statement. And yet…
This is the I Am Legend I recall from many years before, and at the same time, it’s not the I Am Legend I recall from many years before. For clarification, I have not seen The Last Man on Earth or The Omega Man, but I’m beginning to wonder if maybe I’ve read some homage to Matheson’s original work. Here’s some of what I recall, in the hopes that a reader can point me to the story I remember:
(Oh, and if you haven’t read I Am Legend and you plan to go see the Will Smith movie, there are some potential plot spoilers ahead, so you may want to stop reading now, since it’s likely you cannot help me anyway. Thanks for stopping by, though!)
+ as in the book, the story I remember takes place in Los Angeles, only the Neville character is living in a house on a hill, and has an actual moat in front of the place, so deep the vampires can’t cross it. I want to say he even bulldozed the dead vampire bodies in to the moat.
+ I recall the story mentioning the vampires having blue tattoos.
+ the story was obviously more recent than Matheson’s, since it has the Neville character watching a video of a plague victim, the Ben Cortman character, actually becoming one of the vampire creatures.
+ the Neville character has a dog that goes around with him, as we’ve seen in the trailers of the Will Smith movie adaptation, as opposed to the dog Neville tries to befriend in the book, but which ends up attacked by the vampires.
+ the Neville character, while foraging/hunting in the city, is trapped by a snare attached to a light pole. He spends a lot of time trying to get free, so much so that the sun begins to set, and vampire dogs come out. The Neville character’s dog defends him while he frees himself, and is mortally wounded. This also looks like it will be in the Will Smith movie, and seeing this split-second snare bit in the trailer is one of the memories that jostled me to re-read Matheson’s book.
+ the Neville character goes to a park to wait for any survivors who might still be alive; he leaves signs tacked up all over the city with the when and where.
+ the Neville character discovers a female survivor, very much like Ruth in Matheson’s book; except in this story, instead of hitting him with a mallet, she drugs him after learning how to turn off/undo all of his house’s defense mechanisms, letting the vampires in.
+ the Neville character is taken by the vampires to their underground lair, a miniature city below the real city, where he is somewhat put on display, and some of the vampires feed off of him. The Ruth character has a son or little brother, and the Neville character feels somewhat sorry for them, wants to help them, etc.
+ the Ruth character, and maybe others, help him escape, and they leave the city by a sailboat.
That’s the stuff I remember, and that stuff is not in the Matheson book. So where did I read it? I’ve spent a couple of hours searching the Internet for answers, all to no avail. Perhaps my Google fu isn’t strong enough. Perhaps I just don’t know what I should be searching for. But I know I’ve read this story as I’ve described above. Help me, scifi/horror readers. You’re my only hope.