Haha, that's awesome about the interview.
If I were going on a date, I would be doing my best to be easy to have a conversation with. Easy to laugh with and feel comfortable around. So choosing from my wardrobe, I'd wear this pair of white cargo pants I have (loose, but not tastelessly baggy) and probably this white/dark blue T shirt I have which is just tight enough to show my pectorals (which from the sounds of your weight loss, you'll be doing soon
). And I'd swap my boots out for something else.
I think predominantly light colors, or light with a contrast, makes you seem more approachable.
If we were going for some kind of walk or hike, I'd dress appropriately for that, though.