Alot of the mitigation starts with the launch decision in the first place, versus getting airborne and dealing with dicey conditions then. Seems basic, I know, but that's where alot of the issues with HEMS operations appear to be the most prevelant.
I think offsite landing issues are moreso an insurance thing with regards to risk, however the risk is there, especially with brown/whiteout landing conditions that can be encountered with little notice, and which have bitten many a helo pilot. Risk vs reward, a HEMS bird that is transport-only, and isn't doing rescue, there's no real need to land offsite. Survivable or not (dynamic rollover personal survivability has alot of luck factored in, as you're just along for the ride and any host of things can go wrong, since its a crash) the loss of equipment itself, as well as crews, doesn't justify the need.
Hover hold equipment does exist, but may not necessarilyhelp in a cruise flight IMC inadverent penetration. Autopilot would be better, but since these aren't IFR birds anyway (these single-pilot ones such as AS350), no one is pushing down the doors to install one. Training remains the best option, in my opinion, over equipment. If equipment can be acquired or afforded, then that would be an immediate second.
I haven't seen it used for other than you describe; mission decline. And I face the same thing out here: west of KRYN, I have no WX reporting stations at night until KYUM nearly 180 miles west. Daytime, KGXF (halfway between the two) has hourly METAR, but no TAF. But still, that's 90 or so mile areas with no WX reporting coverage. And I've been bitten a good few times at night by that.