What are the chances of finding someone to live in your house take care of your cat for 2.5 months?

I would say pretty good. But there is also a good chance they might be unreliable or even worse they damage your furniture or property. It's a lottery but vet (no pun intended) applicants well.

There are a lot of people doing that. Some websites connect house/petsitters with people in the need; those websites are paid and based on reputation.

A couple of friends do that, right now they are in Kuala Lumpur petsitting a house with 3 dogs and 2 cats. They're coming to Chiang Mai on March I think for a 3 months stay, they have a lot of experience - and referrals - doing that so I can connect you with them if you want.

I'd be interested in emailing them.  I sent you a message.