It sounds like you definitely should be using a yo yo, aka retractable. In construction, you aren't required to have a chin strap because you aren't climbing like that, with hardcore pendulum swings and such. I have seen a crew of rescue guys that were on site have actual climbing helmets, but that's it. I think you are thinking too much and worrying about a helmet when you need to be worrying about using the wrong fall arrest device. Using a retractable with a tie in about waist high would result in a fall to about the bottom flange of the beam, where you could easily get back up from. A 6 foot fixed length lanyard would definitely be the wrong choice for this application, as you are taking a longer fall than needed and a retractable would actually work better on the safety cables because it is right next to you.