Alwayz, don't know where that info comes from, but I doubt it's ever enforced. I certainly know of 1 senior skipper here that lived on his yacht (in Dubai's 'original' sailing club

) for well over a year!
Depending on where you berth your boat, there may also be local Marina restrictions as to how many nights a month you can 'live aboard' your vessel. Dubai Marina certainly has a limit stated in my contract with them although I can't remember exactly how many per month is allowed..... clearly they don't wan't the 'tone' of the placed lowered by people hanging their undercrackers out to dry on the jetty!!
It is correct to say however that even the very best of AC units won't keep you with a cool head when it's 48c and 95% RH during the summer months!
Plenty of cheap villas and apartments are knocking around now, so you'd be best off looking there instead.