I am in shnat avelut for my father z"l (well after the shloshim). My largest customer has asked if I could travel and do some work for them in an East African country where I will definitely not find a minyan. Outright refusal will cost me a large part of my livelihood; I’ve told them my situation and asked that they only send me in case of emergency, which they agreed to, but I’m not sure their definition of an emergency would be the same as mine. That being said, they do supply me about 80% of my income. Assuming the answer is that I can go, the question is, as I have no brothers, should I pay someone to say Kaddish during the period I am unable to?

That is a dilemma. You can go and be there as little as possible. You don't have to sacrifice your livelihood for to say kaddish as important as it is. You should get a replacement by paying someone. I hope you won't have to go.