For the purposes of staying legal I'd say as a general rule of thumb then SCT cloud is fine, BKN you'd almost certainly be illegal - especially as holes have a nasty tendency to fill in just when you don't want them to (and it has happened to a few people).
The thing to remember also is you don't descend vertically, but horizontally - you might be able to see the ground 8 miles away in your example, but if it's a hole is it going to be wide enough for you to stay in visual contact with the ground and comply with the minima for distance away from cloud for VFR. You'd be surprised how big a hole needs to be to stay legal.
And as for 7/8 days - I think you can safely say that you wouldn't be legal - you couldn't be clear of cloud enough as I've pointed out above (and 7/8 can become 8/8's very quickly.