In my case it is for a business visa. Normally I spend my time at Chiang Mai immigration at the beginning of the last month of my visa validity. Once I have passed their hurdles and everything is in order they send my kilos of photocopies to Bangkok and I am asked to return between 6 weeks and 8 weeks later, normally one month after my original visa expires. My passport is stamped accordingly. This year during that time I will need to be out of the country and that gives me concern because I want to get back in without a 30 day tourist stamp. Has anyone else experienced leaving the country during this process?

Apply for a Re Entry Permit from Immigration. 1,000 Baht.

Make sure you are back in time to visit them on the date given.