It's not currently possible to place icons off-route, however I'm pleased to say that we're working on adding this functionality to the webite at the moment. It should hopefully be available in the next few weeks.
First of all great tool you have here.
I'm in charge of the route/sign planning for our small local bike race. I have added icons on the route so our volunteers know where to place them and which ones. But we also need to place signs outside the route to alert traffic to be aware of bikes near by.
How would I do that - if at all possible?