If you can do this, and stick with it, I think it would be great. You could do a poll of the different days of the week, and ask for the good times to do a weekly show. Then, take the time to schedule co-hosts to talk about different topics, and post the upcoming co-host(s) and topic(s) on a dedicated thread a week prior to that show, so people can come see. Don't think that the show has to go on for several hours. Many good shows are 30 min, 1 hour or 2 hours. That makes it much easier for guys with tight schedules to work around their other commitments to go to your show. Of course, this also makes it that much more important that the show be of good quality and have a lot of good info. You shouldn't limit it to people from SP.com, either. Go on YouTube, and ask YankeePrepper, or SouthernPrepper, or *insert name of knowledgeable prepper here* if he/she would be willing to cohost and provide good info. Let them know it's a timed show, and live, and they might be more likely to do it.
Just my two cents' worth.
If you had a scheduled show with previously scheduled topics and knowledgeable cohosts that lasted for a certain amount of time, I would most definitely go a few times and at least check it out. If not, well...I usually just go to BlogTV shows if they already have interesting topics to me or if I literally have nothing better to do. Mostly, there is about 3 hours of offhand BS for every hour of quality info. In my opinion, and not saying they're bad. I do like them!