Stop me if this is already in game and I hadn’t noticed. But Rails, (rail-like objects, tables, benches, etc) probably shouldn’t appreciably slow someone with the skater trait. Just give them a greater chance to be knocked down if attacked. (Or a chance to just eat street if you’re NOT a trained boarder / blader)
The Parkour Expert starting trait already does this. I have a character preset with Fleet-Footed, Quick, Indefatigable, Parkour Expert, and Skater that lets me casually kite & pierce entire hordes using reach weapons.