I like the points made in Barb's post #2 above and would like to add a point about timespan.
You could estimate the time it would take to process your backlog as a background activity - 3/6/12 months or whatever. Then do a fast run-through of everything to be sure there's nothing in there that can hurt you within that *same* timespan.
Add an item to your calendar to remind you when time's up, in case you take longer.
Hopefully, this would achieve the GTD goal of having an infinite amount to do, but not feeling overwhelmed.