Many thanks for the valuable clue of which species fly in Guyane. Armed with this knowledge, I looked beyond my own rearing experience/references, and contacted a Brazilian friend who has bred Opsiphanes cassiae, the chenille of which I had never seen. Thus, I am happy to report I was WRONG – your above photos (and second link in my post) show O. cassiae, not O. tamarindi. (Last-instar larvae of cassiae and tamarindi are nearly identical in appearance, except that cassiae have black tips to their coronal projections, while tamarindi caterpillars more or less lose this black coloration upon reaching their final stadium.) Regarding hostplants, O. cassina, O. invirae, and O. quiteria are known to all use numerous genera of native and ornamental palms, with stray records of Musa for cassina and invirae.
Thank you again for teaching me, François!