Stuffing wood wool in vinyl

[chairs4u]

I've been in the biz over 12 years and am in need of your advice. I took on a job to recreate a '50's ottoman in vinyl. THe original was stuffed with wood wool or sometimes called excelsior. I've tried wetting it with a water & glycerin mixture and re-stuffing into new cover..with horrible results..lumpy and out of shape.
Next I bought 4" thick 7# bonded foam, cut slightly smaller that cover, hard to get it into the cover. Didn't use vacu-form as it's really dense foam and didn't think it would compress. So I removed it, trimmed another 1/2" around the perimeter. It fit but now have the gap to fill between foam and vinyl. ARGH! Oh, and there are 2 sets of buttons that go through the entire piece. So what would you suggest? Heat? Vacu-form? Dacron on the sides?
Thanks, Debra