Do you seriously think a 12GS is going to reliably hold up with the way you will ride it off road? You want to depend even more on electronics - to control and regulate your suspension???
Do yourself a favor and either get a proper set of forks and narrow 21"/18" wheels on the F8 or just get a KTM 950/990 already. Just be aware that like any bike it will also require a list of mods, e.g. the wheels on the Adventure are just as soft as the F8, only the 950 SE has good rims on it stock.