Would this work for you - or is not specific enough?
Hardship/Location Allowance
A payment made in recognition of “different” conditions prevailing at the host location. Locations are assessed for their degree of hardship and the criteria may include isolation, special health risks, extremes of climate and political instability, for example. The allowance is usually expressed as percentage of base pay.
http://www.pwcservices.com/expat/glossary.htm
You may also like to consider the term "hardship country":
Hardship or site allowance. This payment is given to expatriates who relocate to a country that is designated as a "hardship" country. (page 485)
http://books.google.co.uk/books?id=3JJA0G9J5GEC&pg=PA485&lpg...
Perhaps simply "hardship allowance" would be sufficiently clear in your context?