Just such a crazy thought may, but okay, the book writing drifter exists and he was out there months before SG came to Oak Beach, fine. But if JB found himself a new drifter, the original one wouldn't know. But when asking the neighbors afterwards, they all would say, there was this drifter, his name was ... and they would refer to the drifter they remember.
There is one thing, that makes me stumbling here and the book-writing drifter indirectly confirms it. JB was asked in the lie-detector test about his intentions to have sex with SG. And when he said no, the device could either have shown he lied, shown something, nobody could interprete or shown, he said the truth. However, if the answer and the result on the device is totally against the expectation, operators would may estimate the result as "inconclusive". So if JB said, he had no intentions to have sex with SG, and the device said, he said the truth, LE would tell us "inconclusive". The idea, that JB rented himself a prostitute to have not sex with her is for most people just too abstract. Unless of course, JB got SG because he wanted to kill her n the first place, one could may argue. But it would be a stretch too.
Now, the drifter writes about JB collecting




. All kinds of. So, he is basically some kind of voyeur. He gains sexual relief from seeing. Not necessarily from doing. So, assuming, JB wanted to see that night too, he would have needed someone to have sex with SG while he watched. Which would explain the lie-detector result as well.