Can I travel to Thailand for 2 months, extend my stay, and return after visiting a neighboring country?

Go n get the right visa.Average tourist stays only for 3 weeks

60 day tourist visa got changed this week to 30 days!

If you check the Thai consulate in Athen you may receive a most updated information for you. The information from my consulate differs from the information provided in many FB groups, e.g. requiring a return ticket, limited annual land boarder crossings to 2 but no limits by air, requirements of 20,000 THB in cash. They even point out that even a visa is not a guarantee to enter Thailand, it is always on the descration of the immigration officer infront of you. You will find people with several land crossing without problems, few other may get stamps to leave Thailand within 7 days. You can't expect a reliable answer, even not from me citing a Thai consulate. The reliable answer comes from the officer infront of you.

IF you get visum exempt entry the second time (depends on the mood of the immigration officer, because 60+30 and then a border run to get the same again, is not really the behaviour of a tourist), the 'extension' will be 7 days... It is not really an extension, but just enough time to leave the country...

I recommend you get a proper visa. That is what the Thai Government is looking for now a days.

You don’t need a return ticket but your airline may insist on an onward ticket within the 60 days. Immigration could ask but generally don’t unless you have an extensive history of entries.