Have just read 'The Loved One' for the first time - very funny, very macabre.
Christopher Sykes, in his biography of EW, tells us that Waugh's American publishers were indeed concerned about the possible reaction in the USA and, specifically, the likelihood of being sued by Forest Lawn. Waugh was helped out by a titled friend who agreed to change his will, asking to be buried in Forest Lawn, having been, to paraphrase "... so impressed by the description in Mr. Waugh's latest novel"! Waugh's agent AD Peters showed this to the nervous publishers who were, apparently, reassured by the enthusiastic burial plans of EW's upper crust pal. I believe there was no great outcry in the USA, I don't think Forest Lawn did make a fuss and, some years later, EW's friend quietly removed the Codicil from his will!