No confirmation about coveralls or boots being found anywhere has been released to the public that I’m aware, nor any data on what he was wearing in the truck stop video.
There are a few businesses with cameras, right next to Wiechmans to the east, and two across the street just to the east, that would have captured his truck. No official report on which one did, but some have speculated it was the business right next to W.
To get to W via an alternate route he would have had to have gone way out of his way in a big loop from the west through Sac City (with more potential cameras). His phone data was reported as showing that didn’t happen. The times of the pings, etc., showed the phone moving west on 20, never heading south on 71, spending that extra 12 min or so around the intersection of 20 and 71, then its final destination where the truck was found. The phone data showed there was no time for him to have gone to W and back to anywhere like where his truck was located.