You may be approaching this the wrong way around, even though I am involved in property sales, the first piece of advice I would give is that, if you have to rely on income from rentals, to fund a property, then don't buy, especially in golf resorts which tend to have higher comunity fee, and there is a lot of competition for rentals with low rates offered
Rather than saying that you nned 18 weeks you should look at the ACTUAL rental rates from areas and then the actual costs
Starting with ALL of your fixed costs, community fees around €100 a month, non-residents tax of around €400 a year, your loca;l rates €300, the tax liability of rentals and you will need a property manager,arond €300 a year and finally the standing charges for water and electricity, what you pay regardless of comsumption, around €30 a month
No agent will give you 18 weeks a year and you will have to work hard with your own marketing with siyes like owners direct, Holiday Lettings and other sites and they will either chrage you anually or take a cut of the rental, the use of power and water can make a dent and if you don't control the AC use, with a meter, then you could rent at a loss
Consider all of the options , perhaps a beach apartment, near a golf course, where the fixed costs are lower, could be a better option