In DIY fashion, Hand-Crank USB Charger
If it's just some extra power you (might) need, why not try something other than a solar pack? Like a jump charger maybe?
I got mine for $7.99:
They also have little baffles that strap to your pack and charge while you're riding at Outdoor Gear & Clothing: The North Face, Marmot, Patagonia & More Gear Brands | Backcountry.com They go on sale for about $25 too. Lightweight enough to not notice and they fit in your helmet pouch on a Camelbak.
DP - Sorry, can't find the one I saw on Steep and Cheap that was on sale a while back on Back Country's site.
I wasn't sure if you are going day trips or overnighters. For overnighters, this is good. It's heavier than a standard Jetboil though.
BioLite CampStove - BioLite Stove