Heater channel woes

I guess this is normal for classic Beetles... finding worst rust rot than you thought there was. I started working on it yesterday by removing the front passenger seat and running board.. and what I found isn't very pretty. It looks like this thing is going to need heater channels... or at least one on the right for sure and a patch on the left one. The left one seems only to be rotten at the very back of it at the wheel well area.

I knew the right floor pan was rotten out when I bought it, that was a given since I see through to the ground. Someone did some crappy patching attempts with some thin pieces of aluminum and a piece of rubber or something. Maybe they wanted to have the Flintstones braking system.

Photos of the right heater channel:








Here's some underside photos of the left heater channel. Doesn't look rusted at all toward the front and seems very solid, but I haven't removed the running board yet to see what the side looks like:




Some shots of under the back seat where the body meets the heater channels. Needs patching:




Here is a pic of my helper, Benny: