Yeah - when I first started traditional 10 years ago my feet really hurt at first from climbing the ladder, but it was from wearing trainers with thin soles. Try some thick insoles, skateboard trainers or hiking boots(although I always think hard soles of hiking boots are more dangerous for ladders as they can slip through the rungs easily when wet).
My feet really hurt at first when i switched to wfp last year - I think it was because they weren't used to being on the ground all day! I've been wearing skateboard trainers with thick soles and that did the trick! Although I think i'm gonna get some hiking boots as they're a bit more water-proof!