Seaplanes or Amphibious Aircraft for Caribbean Adventuring and Logistics

[Icelander]

Assuming that Kessler obtained a Be-12 amphibious aircraft shortly after the fall of the Soviet Union, what is the most reasonable way for him to be able to use it?

I get the feeling that the FAA certification process in the US is absolutely not worth it for just one airframe and registering it as 'Experimental' would make it useless in that it would be confined close to its home field.

Since airplanes registered in a foreign country can fly through and land in territories where they are not registered, what are the practical limits on that?

For example, if an aircraft charter company was established in some Eastern Bloc country (or somewhere else in the world where a Be-12 is legal for commercial purposes), are there any limits on how long-term chartering an aircraft for them for use in another part of the world can be before you need to register a local company that is officially leasing the aircraft?

Say, if Kessler wanted the Be-12 to travel between various Caribbean islands to be available for SAR and medevac for certain 'Night Rider' (Monster Hunter) operations, could it just be registered in Russia or somewhere like Angola, Namibia or somewhere equivalent the entire time?

Also, does anyone have a rough guess about the operating costs for the Be-12?