Outside of winter and in the spring many people leave their cars overnight at the side of the road near Diamantina Hut, which is the start of the Razorback. I'm not sure of the legality or practicality of this during winter tho. There's probably not enough space, not to mention potential damage from snow plows n stuff.
As Nezumi said, the overnight parking and shuttle busses to central are probably a better option.
There was no shuttle to Loch carpark last year, but this year its meant to be "open" enough that its useable, and I believe that suggests that the busses will get you up to there.
However even from there the walk won't be so nice with cars trucks and buses going by.
Seeing as you're already going backcountry, I thought perhaps a tiny bit more effort for a different route might be a more interesting adventure:
Park at overnight parking and take a bus to central.
If you can bus to loch, then just bootpack or skin to top of summit chair (Purple, 200m, I'd probably skin rather than bootpack).
Otherwise take the lift or skin to summit chair to summit (Blue) (I'm not sure of the rules skinning inbounds, I'd suggest just make sure you skin out of the way, eg along lookers right outside of the jbar and under roadrunner chair).
Bootpack or skin to the fire lookout tower. Its almost dead flat, 800m. (green to green circle).
Remove skins, board down to edge of resort boundary and chuck a right to drop down onto the road right next to razorback (green).
The clearing you can see on the map there is a mini avalanche path so it can be a bit steep and slippy and rocky and damage your gear (red), and the trees past that point can be hella tight and filled with ice and impassable (orange), but between the two I bet there's still a way to ski straight to Diamantina Hut! At worst, take skiers left right next to the red avi zone.
I've considered heading to Razorback either of these ways before, however I usually only do Razor at the end of the season, which means we just drive there instead. However I do very frequently ski to this same route from summit past the resort border to access Dargo Bowl and Baldy Creek carlaps. Its icy windblown crap, often quite thin, but its not a difficult route.
Do the reverse on your way back home. Head back to Hotham Central and walk through the village.
Skin up Higginbotham from the back of the village 550m (end of yellow) (a little bit around from behind Razorback apartments there's a national park summer zig zag trail up there, youll probably see existing tracks going up it, dont be tempted to go through the trees on the west they'll close you out).
Cross the flat top of Higginbotham to the top of Big D chairlift.
Ski down to the bottom of the chair.
Go to the Genny and have a beer
and then catch the bus back to overnight carpark directly across the road from there.
If you remind me later in the season I can check if busses are heading to Loch for you. They don't start running until June long weekend I think.
