I've also heard airport novels called trash/pulp fiction. They are, naturally, the sort of mass market books sold in places like airports and dollar stores. They are novels written to appeal to a wide audience to ease the boredom of travel. They have simple vocabularies, are often fast-paced and showcase exotic adventures, and are printed very cheaply.
I've always thought that until relatively recently, reading for pleasure was a thing reserved for the upper crust. Is that true? If it isn't, what was an early example of a book that was widely popular and accessible to the common person? Who was the first John Grisham or Tom Clancy?
Penny dreadfuls, dime novels, and the like might meet your criteria. There was a big market for gothic horror, whether Varney the Vampire, Wendell the Werewolf, or Sweeney Todd the Demon Barber of Fleet Street in the Victorian period. They also had their "sensation novels" about wife-beating and other societal problems. These were all considered cheap and sleazy and not good literature.
There was a late Georgian horror fad that left us The Castle of Otranto, the novels of Mrs. Anne Radcliffe, the nickname for "Monk" Lewis (he never lived down the spectacular success of The Monk), and eventually Jane Austen's satire,Northanger Abby.
The sales for most of these were put over by the middle class, who had the money for books and the time to read them. It was normal for women to read them aloud together taking turns, especially in families. Sometimes one read while the others did mending or fancywork; sometime they just gathered around a table with a lamp and gave it their full attention. If Father read aloud in the evening, it might be shorter comic pieces, or more serious literature.
Moving out of my specialty in speculative fiction, you might consider Richardson's Pamela or the take-off Tom Jones. They might be considered literature now, but in their day I would call them pop novels.
As to size, they were often published as three volumes, each a convenient size for coat pocket or reticule (or hiding between the sofa cushons), about the size of mass-market paperbacks.
So definitely you have pop fiction in the 1700s in English. It was helped out by the development of the subscription library that let you borrow books you wouldn't read twice.