Bunny flat parking area is highest at about 7k. Weather station says about 200" so plenty deep. Take a look at the map on the bathroom that outlines wilderness vs legal riding area. No grooming in the area but some really cool terrain can be easily had.
Can park overnight if that is what you are looking to do.
There are several other areas off of Hwy 97 (Deer Mt.) or outside of McCloud (Pilgrim Creek) that have developed snowmobile parks. If you google you can get intel on those 2. They drop off about 5k and access country between 5-7k elevation. Miles and miles of trails and some fun play areas.
With the storms this last week, anything over 5k ought to be hoot and plenty deep.
There are other undeveloped areas, but it wouldn't be advisable to venture without someone who knows them.
Heath provided great info. Are you looking at coming down this season?
I would add that Bunny Flat is very limited. Coverage is amazing on the mountain currently.
Deer Mtn you drive up the road about 1/2 mile an unload at the snow line. Still plenty of snow to ride that area. I unloaded there on Friday and there was 1 1/2 feet of new and it has continued to snow since Friday. Ash Creek Butte has some good areas to ride.
Pilgrim Creek you have to drive past the park but I heard once you unload at the snow line, the snow depth is still great.
Riding out of Pilgrim Cr and Deer Mtn you access the same areas.
Currently access to the Eddies, mtns on west side of I5, is poor. Lots of south facing pavement so you have to ride lots of bare pavement. Once snow melts out you can drive to snow line and unload. Eddies, in my opinion, are our best riding areas.
All good info. I hope you aren't planning on coming all the way down from Bend just to ride Mt. Shasta though. Like said, it's limited. They ruined that mt. when they made about 99% of it wilderness above the tree line. We get one little draw to ride compared to the huge amount of mt. it is. It's gorgeous country, but all that is available to ride on Mt. Shasta itself takes about 1/2 to 3/4 of a day. The other areas have some fun stuff, but they are kind of on the flanks of the Mt. Or completely east of it. Except for the Eddies and the Castle Craig's areas. I've never ridden those areas and I admit I like to go ride Mt. Shasta but only go when the snow levels are so high I can't ride around Susanville anymore. I usually only go once a year at the end of the riding season.