Training (hiking) options near Billings; easy winter access

Hi all

I'm getting into mountain shape for an attempt on the Grand next summer and need to start hiking uphill.  The biggest hill within 2 hours of my home is a whopping 200' of vertical gain.  Luckily, I'll be traveling in/out of Billings for a bit (towards Crow); I'm completely new to this area.  Any locals have recommendations for simple hiking trails that get good elevation gain?  I don't need the prettiest route or freedom from crowds (or a summit, I can take laps on something smaller).  I need something (relatively) easy to get to before/after work or on off days and I can get to in a rental car during winter (could have option for SUV or pickup but who knows with rental cars).  Generic google searches don't help much understanding local winter parking/access.

Thanks!

Go to Red Lodge and showshoe up the Hellroaring Road to the plateau - its a lungbusting ascent with thousands of feet of gain and lovely views. Or trudge through the snow up the Bear Track trail.

Many other trails in the Red Lodge area, Boulder River, other places in the Beartooths. 

One thing I used to do frequently when I lived in Billings, during the pandemic when a lot of things were closed, and I didn't always have a reliable vehicle, I'd leave my house in downtown, walk up through a neighborhood to the path alongside 27th street, walk along the rimrocks all the way to the end of Zimmerman Park, and back. 16 miles round trip. 

If your gym has a stairmaster, throw a 30-50lb kettlebell in a pack and start walking. It's the easiest way to control and track your progress and, IMO, it is more effective than anything else. It might not be the most fun but it'll whip you into shape real quick (and you can watch movies/read while suffering :D).

Thanks Aaron, lots of helpful stuff there!

And Patty I agree, I've done the weighted stair climber thing in the past, but since I'll be in a place with some topography I want to save the indoor suffering for when I have no other options.