A stereo doesn't draw much.
A rechargable battery/inverter inverter unit would probably be cheapest
if you plan to do a lot of it, long term.
'Trouble is' batteries are expensive.
A good battery, properly sized, will last a very long time and not suffer damage
if left on a 'smart' battery...
Careful. Where in Colorado?
(Used to be one of my favorite places until the 'BMWs & Beansprouts' crowd arrived.
Those will include PETA types who just can't bear 'hurting cute little animals', pests or not.)
In a town you are likely to be discharge of weapons laws that these types will want...
The biggest one that will fit, and for which you can fabricate mounts
to line it up with your rear sprocket.
Then you get to bend pipes and mess with a wiring harness.
You might want to re-think that.
All-weather riding gets old real fast in the north-east.
70-80 can be fun for short trips on a 'naked bike' but the buffetting
will really wear you down on longer trips.
You'd want something with hard cases, a back rack, and a fairing,
if you want to try it...
Meat: Strong flavor, an aquired taste.
Population control: Bears may be visually appealing, but not too safe to be around.
This is a solitary oportunistic omnivore. They're not 'wired' for social interaction,
and this renders them more dangerous than most animals.
They have learned to fear man...