With regard to leaving the leaves on the mulch beds - I thought of
this. However, leaves decompose and cause fungus as well. This can
bring soil diseases that can kill the surrounding plants. I would
prefer to have a depleted mulch bed than to have dead plants.

As for the tarp idea, I do this in my backyard as it is the most level
portion of my yard and I have to drag all the leaf bags to the front
and down the hill. However, it does not solve the problem of saving as
much mulch as possible in the process of extracting the leaves.