[Grey Lady]

You didn't say which direction your traffic is going. I've found with ramps/steps they are safer if your visitors are going up it towards the scary stuff rather than running down it from the scary stuff. Even if they have to come down a couple of porch steps it is probably safer than running down a rather steep ramp. I think your answer also depends on your scary factor.
However if the ramp is the entrance then you are left with the problem of rain, then if it's wet what do you do with your entrance?? oh the trouble of being a haunter!
Now I'm flip flopping,

 

[Grey Lady]

Reading your explanation of how you got the ramp, reminded me there are truly, good and decent people in the world! Thanks for that.

Regarding the excellent idea of using tree branches to cover the ramp, you could contact a local tree service and see if you could get tree branches from them just in time to decorate for Halloween.