I will try to clear
Source 2 is completely wrong.Only your close family and your friends who stays with you/with a member of close family is accepted as free of charge.Free of charge accomidation is very unclear,open to abuse situation for tax office and they clearly explain border of free of charge accomidation in tax law.
Source 3 has a lot of different informations but as i see it is writen there to speak with and certified accountant or with tax office to get blear information about tax side.You can get information from tax office easily if you are in Fethiye as well.
I understand your point,your friends come to your home,having holiday and you dont charge any money.But our tax laws not accept a benefit of something as complimentary.
At G.V.K.(Income tax law) no:73 says:'' Bedelsiz olarak başkalarının intifaına bırakılan mal ve hakların emsal kira bedeli, bu mal ve hakların kirası sayılır.''
Basiclly it says,imputed rental cost will be calculated and accepted as income for free of charge benefits.if they make a control to your property and find out some one elses stays,they will make a valuation of market rental prices.And it will be accrued income for you.I am sorry but this is what tax law says.
Also you are not giving around 2500 lira to your accountant.that amount consist of accountant fee,duty stamps of V.A.T.,witholding tax,pre-paid tax,income tax declaration forms.These are standart payments when you registered as a tax payer in Turkey.