Upgrading to a dif Toilet, Flange is stuck???

The Rv is on the other side of town and I'm going by memory as I had to reinstall the old toilet (as my Mother in Law is living in it). I'm pretty sure that the inside is flush (with a seam)in transition from the flange, to the downpipe. I could be wrong, but am pretty sure. Is that how the screw in one's work?
Anyway, I like Dougs suggestion as I DO have a straight down pipe, I can see the bottom of the tank easily. I"m just worried that if I put clockwise pressure on the downpipe, then if it breaks loose from the tank I have a bigger issue. It currently is NOT loose from the tank, I'm assuming as the pipe won't put upwards (and it's straight down). I figure the only thing holding it is the connection/seal to the blk tank. I would like to see a pic of the "slitting" and peeling the flange that you mentioned before. I'm thinking once that makes sense to me, I will try 'unscrewing" it, and then if that doesn't work, I'll slit and pull it. Just can't picture the latter yet. Problem I have is I only have one day to do this, and once I pull the toilet, I have to complete it that day as it's used regularily. jeff