Nice spot of kemming there @Cylindric
I gave this some thought the a while back (but haven't made it along to the space since or made time to post about it). One consideration is that anything we do probably needs to be approved by the Boileroom.
My idea was to go with a discrete but noticeable sign by the gate and then to use something like these (in purple):
They'd be reasonably discrete, but provide a breadcrumb like trail to the space for anyone who's trying to find us.