Yeah troppo go for it, cross pollinate them once you have both mature. And grow up the seeds and select them. That's what I am planning on doing.
A good aid for the injection issue present is a Sailing boat

a 30ft kathamaran would do the job of crossing the water. Eventually airport customs most likely will abandond rigorous injecion status checks, to cumbersome even with digital automated systems I believe.
Even if you get the first fruit at 5 years it wont be many fruits (from what I have seen), probobly still 10-15 years for decent yeilds and average economic life of graftage isnt much more then 30 years.
Wow that Zibethinus X Lowianus is something new! Thanks for sharing that as I would have never found it since can't type thai.