I adapt to the situation I am faced with. If I am trodding around a highland games I never have anyone touch my kilt. Go to a kilted event and someone may inquire whats under, but most won't lift it.
If I go to a pub there is a chance there might be one lady or goof wants to see. Hasn't been a problem yet but I don't take the chance. I had one guy grab the bottom of my kilt recently, I told him quietly and calmly in a joking/ not-joking way that it wouldn't be a good idea. He got the point.
A goofy pair of briefs might be the ticket. Maybe something that belittles the person for lifting the kilt in the first place. We need briefs that put the joke back on them. Make them feel more embarassed that they did it than you feel to actually have someone do it to you. Someone come up with the slogan and we can go to print. X- marks kiltlifter briefs. Put the shame on the shamer.

Kilted Stuart