It'll work out. Are there any dangers? Sure. They could be working and leave their computer unlocked, then BAM, they're in your company's network. It's the same as anything else, and the level of risk that your company is willing to take.
Personally, I'd reduce the 18-character password to around 12 characters and have them fill it in each time (or have it sync'd with their LDAP/AD), but that's just me.