your original post asks about rental yields and by definition, the more you spend on the property, the harder you have to work to acieve a decent yield. Most renters do not want lots of space when they come on holiday, a place to sleep and maybe a communal pool are sufficient. Also, ask yourself what would you want on holiday? Easy access from the airport, close to beach/golf and not in the middle of nowhere cos you can’t buy a pint of milk or a Daily Mail.
Personally, I think your assumptions are about spot on, 8-12 weeks a year is about right but you have to spend out on a bit of advertising.
The only thing I disagree about is buying a 3 bed place, you won’t get 50% more rental income than if you bought a 2 bed place, but it may cost you 50% more to buy. The best yields are achieved in this way.