Shorts would be very tempting during our June bear hunts or early season elk when temps can be hot. Shot a couple spring bears in a T shirt and have rolled my pants up to cool off while glassing on multiple occassions. Called in my last elk and killed him on a real hot day in a t shirt. Can't imagine shorts would have made any difference to the elk ( would of made me a hell of allot more comfortable).
Whatever keeps you comfortable and keeps you out there hunting is the right choice.
Last cow I shot was a frontal shot at 15 yards. Cow-called her in, wearing black shorts. She was looking in my direction, scanning for the other cow, when she came in. It was about 60 degrees out. After she went down, a nice 6x6 came in to about 40 yards and just stood there, looking in my direction to see what all the commotion was about. He never did find the "other" elk that had been talking a few minutes earlier, so he turned around and walked away. (I could have - and would have - shot him, too, but I already had one elk on the ground, and didn't want to deal with two elk, solo, in one evening!)
Shot a nice 6x6 bull in NM, wearing red shorts and no shirt. 21 yards. It was 92 degrees out, I was sitting over a water hole, under the shade of a pinion, and the wind was right.
Shot a nice 6x6 bull in CO, wearing red shorts and a blue t-shirt. 40 yards. It was noon, and I was hiking uphill, moving locations to a different hunting area on the mountain range. I took a break for a drink of water, gave out a few cow calls, and he came thundering in. I was near a bedding area.
Shot a cow over a natural spring in CO, wearing a camo t-shirt and black shorts. 13 yards. About 2:30 in the afternoon.
I've got a few more....which are pretty similar....I think you get the idea!
As long as the wind is right, and you aren't moving a significant amount, the elk really won't notice if you have fabric covering the lower 14'-16" of your legs.....and they probably can't differentiate between legs and normal underbrush, anyhow.