Yikes...... you just described my neighbours
As you see, it is not unrealistic at all.
At most the gang just needs avoid living in a deeply conservative area where neighbors would not mind their business with a group of polyamorous models/artists living a kind of 'rocker' lifestyle (F and Georgina seem responsible enough to keep the group away from substance abuse). Otherwise, they would not look that weird for showbiz people.
F and D also have to cover their background from media probing with some decent change of identity. Probably relatively easy to do with some wealth to throw around even if they become celebrities, since D and Elena had fairly sheltered lifestyles with a likely limited data trail before the story began, and D and F had entirely separate lives in different countries for a long time. It would probably be not too difficult for F and D to adopt the background story that is actually true for F and Elena: they are strangers that first met and hit it off during a vacation. Of course, Rachel, Brad, and his family would know, but hopefully resolution of their subplot shall leave them in a bad place where they are powerless to threaten the gang even by spreading malicious gossip (more or less as it happened with Lucas).
The harem modeling agency arrangement would make it fairly easy to include even more characters besides F, D, Elena, Jen, and Gina in the polyamorous 'family': Cassandra may become a second photographer and/or assistant manager (esp. if Gina does not care to share administrative duties with F); Margot might be their trainer and/or bodyguard. Koko might be a regularly visiting friend with benefits: she has expressed sexual interest in F and sympathy for D, people from different branches of showbiz often rub shoulders, and IIRC D has been hinted to have some singing talent.
I guess the beach vacation country is too far-off to run a modeling agency from there, but the gang could easily make it their main holiday spot. Not sure where they would best set up their residence, but someplace would fit that is socially liberal, conductive to modeling business, and optimally has no laws against incest between consenting adults (so that police never needs to get involved even if rumors surface).