Set up concrete blocks, wooden boxes, or the support parts of a Reebok step to the right height. Set your loaded barbell outside the squat rack on these supports. The plates will fit right in the middle of the Reebok step supports (assuming your not using powerlifter loads, which might be too much for that particular type of support).
I think I'd feel more secure with my feet on the floor and finding something of an appropriate height to set the barbell on. I also don't think using DBs would carry over to your conventional deadlift very well.
We discussed this a little bit in this thread:
Strength II Substitutes