no infos about that . ( meaning the end of civil war you mentioned )
but you might know civil war in Burma started in 1962 . since then the Mae Sai border has been opened from time to time . I went through it more than 30 times over the years . so .nothing wrong about enquiring .
I myself went through a few times when it opened for a few days , and gave the info on this group ,so maybe somebody can benefit .
I recently found an other option , but I think I'll keep it for myself this time , to avoid sarcasm .