Looking for some friends in our Thailand.

Hello,
I am Janek from Wrocław- Poland.
I want visit big part of Thailand ~30.10.2017y.
I want make a journey fith my good friend.
We want to buy 2nd hand scooter inside and cross the borders of Cambodga and Laos too.
Looking for some informations about it.
Looking for some friends/ contacts who can help me inside.
Mostly with leanguage barrier.
I am From Poland, instead I can speak about living in my country and Countries close to my border.
;)

Hi. I dont think you can cross borders with a scooter without a mountain of paperwork . Public transport is cheap and relianle .

But i want cross more then 3000 kilometers, so i want buy my private vehicle.
Don't want to rent becouse i am not sure about condition after back. It's cheapest to buy and lose own scooter then Pay the penalty in renting office.
What kind of paperwork exactly? I am in Asia for 2mounths.