Stash busting and yarn subbing

I'm trying to do a bit of stash busting and knit exclusively from my stash. I recently documented just what my stash contains and it was a little scary so I'm embarking on a further effort to knit it up and reduce it.

This current project should put a bit of a dent in it as it's a chunky yarn. Guilty admission: it is a wool acrylic blend but it is actually nice and soft. I have 11 100g balls of it in this beige. I bought it to knit a cardigan for Andy, obviously it was on special, but not sure why I thought Andy would wear a beige and red college style cardigan (the yarn has been sitting there for maybe 7 or so years) I also have 2 100g balls of it in red.

Anyway, I'm knitting this poncho which comes from the Jo Sharp Contemporary Knitting 2 book. It would be very lush in the JS Silkroad Ultra but it's still turning out quite nicely in the sub and it only took me a couple of nights to knit half it. Only problem is that it's not wide enough :( I got approximate gauge with this yarn on the suggested needles for it; 6mm. But the approximate is not quite approximate enough. :(

SO my options are: frog it back to before the short rows that create the shaping at the front and add in some extra width. Or frog the lot and knit it up on 6.5mm or 7mm needles ~ although I'm not sure if I'd like the looser weave on the bigger needles and it might make it stretch too much. The length is pretty good as it is but it would be fine longer too.

What to do????