Welding on a frame

[1940Pipercub!]

Hello all! I have a question that I am hoping folks on here may have more experience than me regarding welding on these squarebody truck frames. I am aware folks weld on these frames during thier builds and they don't think twice about how GM stressed relieved or perhaps normalized the frames after the stamping process. Has anybody ever thought or seen these frames crack around a weld repair due to the natural twisting/flexing these trucks encounter on the roads (not rock crawling)?
I have a 1985 K20 that has some pretty good pitting on the lower flange of the frame rail (about 3 foot in length). My concern is that welding on a doubler may affect the frame's heat treatment and develop cracks. Am I overthinking this? I would also like to add I am a competent welder. Thank you.