Fall foliage, JR Pass, and also Sapporo

Hey guys. I have a unique dilemma due to my stupid, spontaneous travel style.

I'm already in Japan, and I've been enjoying slow travel through Osaka, Nagano, Tokyo, and Nikko. My JR Pass activates on November 4th, ending on November 17th.

I wanted to use this for travels through Chubu and Tohuku, and I planned everything around a concert in Sapporo for November 10th. Therefore, I have accommodation booked in Sapporo between November 10th-November 12th. I'm swinging last minute accommodation through Couchsurfing, youth hostels, one onsen splurge, and the occasional 24 hour super sento stay. Then I was thinking of taking JAL's $99 discount flight deal down to Hiroshima for the 12th-16th, after which I'd take the bullet train back to Tokyo on the morning of the 17th.

Problem #1: so apparently a lot of the area's fall foliage dies off around this time, which makes that whole Sapporo idea a bit ..inconvenient. ...

Problem #2: I'm less interested in dishing out money for a flight up to Sapporo when I'd rather save that for the Hiroshima flight.

I'd really love some help straightening out this itinerary. I'm interested in everything, from unique nature hikes (Mount Zao?) to onsens, great seafood, interesting small towns, beautiful railways, etc...

Note: my family's visiting me between the November 18th and December 1st, where we'll see Tokyo/Kyoto. I'm not too worried about missing Nara, Kobe, Hakone and the Fuji Lakes during the fall season, and I'm referencing plenty of itineraries there ;)

Thanks so much for any guidance!!! I know I'm asking for a lot...