If I understand well, then I can define the Preterists as modern euhemerizers of an ancient myth.
Their logic is the following:
1) the historical Jesus predicted an imminent Parusia.
2) but the Parusia didn't happen.
3) the point 2 is too much embarrassing to be accepted as true.
4) therefore the Parusia happened. When: with the destruction of the Temple in 70 CE.
5) Only: no one saw the Christ of the Parusia.
Clearly the point 4 is invented. The "Parusia" was only for them a historical event.
This doesn't sound as what an euhemerizer ("Mark") did. This resembles more what the Pillars (the founders of the Jesus Myth) did: they imagined that Jesus was crucified in outer space.
But someone, not Christian, may say: "Is the destruction of the Temple an evidence of the fact that, afterall, the historical Jesus was a true prophet?" Insofar he would think so, he is partially persuaded about the "sound" truth of the implication:
the Jews were punished in 70 CE ------> Jesus was a true prophet.
Insofar we (not Christians) realize what the Preterists (Christians) have done, we can label them correctly as euhemerizers of a previous myth.
Preterists as example of modern euhemerizers
Preterists as example of modern euhemerizers
Nihil enim in speciem fallacius est quam prava religio. -Liv. xxxix. 16.