Todd wrote:

Is there some kind on ramp I can put in from of the sill
so that I do not have to go 6" straight up? Reusable,
portable? Do these things securely hold my dolly with
refrigerator attached?

You could make a ramp, but it's really not necessary to have a perfect slope.
Get a 2x8 the width of you door and nail a 2x6, then a 2x4. Otherwise start with
a 2x10 and sand or saw the slope.