As you all know the PHD Flopper has been confirmed by others that it is physically not possible to get there due to the map's invisible barriers. But I believe you can get through there by teleporting and using the "Flash". During the trailer movie clip before the game starts, you hear the old dude(I can't match their names with their face) who just got teleported by the rift talk about how if they knew about the "Flash" they would kill him, and how nobody can know it. So as you know at usually around Round 5, these "crawlers" would come and you would usually do the trample steam trick or Galvaknckles to kill them and get a free perk. Whenever the crawlers(or I actually believe they are denizens as well? Or a type of it?) killed by trample steam or Galvaknuckles they create a electric spark, or what I would assume a "Flash" or a similar/smaller version of it.
SO, HERE IS MY MAIN THEORY ON THE PROCEDURE:
I would start off by getting points and building the siliquifier and trample steam before the crawlers come. Then I would try to find a spot where crawlers can meet up at the same spot without me being hurt(maybe the wall glitch at side under the box floor at roof? Sorry for those who don't approve glitching). Then when the crawler round starts I would save all the crawlers as they can't get to you, spray siliquifier on the ground: 2 Predicted outcomes:::
1: When the crawlers collide with each other and die they create a huge spark; thus, maybe creating a teleporter when it gets enough charge for a huge "Flash", or it drops end of round with the perk bottle.
2:Then I would need a partner(if anyone is alive, or myself if I could) to place a trample steam on the siliquidfier liquid, that will hopefully cause sparks and kill the crawlers while sliding if collision doesn't make sparks. Hopefully that might create a teleporter.
* I haven't tried this out yet, feel free to try it out! Leave comments! Thanks for reading!