A good used Ural will cost less than having the GS professionally hacked. A good used Ural will also hold its value if you decide after a while to sell it and hack the GS.
You will never be able recoup the amount of money you spend hacking a GS if the need to sell it arises.
I have a GS I was considering hacking to go off-roading as my Goldwing hack didn't like it. I ended up buying a 2007 Ural Patrol with 2500 miles for $6k. I have never had a bike that put as big a smile on my face as this Ural does. I have put 4000 km on it in the 2 months I've owned it, about double my previous normal amount of riding on all of my other bikes combined.
Highwayitis isn't a terminal disease. Even living in So Cal I can usually find a scenic back road. If I have to get on the freeway, the Ural will cruise at 60 just fine in the right lane.
Anyway, my opinion (and you know what they say about opinions
) .... Get a used Ural first
Gratuitous sidecar / dog photo off road at Obsidian Dome near Mammoth