I've bought this dress for a party next month and I am really happy with it. However, it ties up on the inside and then on the outside on the other side (does that even make sense!?) and when I walk / if it's windy I'll be in fear of flashing my pants. Any suggestions for what I could wear underneath? I've never worn any type of slip before - is that what's needed here or am I best off getting a black tube skirt? TIA!