Is it possible to head overland from Thailand to Yangon? I've flown there before, but would like to travel a bit slower. Crappy buses are fine, or I'll hire a driver. 

Do the e-visas apply for land borders as well as airports?

Has anyone done this trip?

Yes;

3 main land borders.. I've entered once by land at Mai Sai, (headed to Mandalay via Kentung) and exited twice from Yangon to 1.Kwathoung/Ranong, 2 Hip-an/Mae Sot

Thank you!