This cannot be stressed enough– ALWAYS guard your light stands, or whatever your flashes may be mounted on. I’ve seen thousands of dollars worth of flash be destroyed by a single skateboard. If at all possible, have a homie watch a flash, even just by sitting next to it. I also suggest buying said homie lunch or a beer for his help, even if he doesnt have to make a flying leap to catch a falling strobe. They are doing you a huge favor, because they probably want to be riding, and you will (hopefully) be making money from the photograph which your homie helped you create. I remember once shooting at a skatepark (horrible idea) when a skateboard comes crusing out of left field and nails my light stand. luckily a grom was there to act fast and grab it, since I was at least 15 feet away from it. I gave him a dollar for his good deed, which I’m sure he used to buy a sticker or a mountain dew. If no friends are available, stack your bag, a bike, some skateboards– anything large and sturdy that will be able to stop or slow down a runaway board or bike. you rollerbladers are lucky– for once.
Another good idea is to buy some tent stakes to anchor your stands into the ground. If you want to get more extreme, you can use string or rope to tie the stand to a nearby tree or higher-up object so that if it is hit, or a gust of wind hits, it simply won’t tip over.