It's difficult to say what the average catch rate is as on Orellana it's so big, 37km long I've known people to go for a week or more and blank, others who have hauled in a weekend.
The best thing to do is get your self a guide even if it's to point you in the right direction. Night fishing used to be illegal,I think now you can night fish if you have a quide who has a license. We used to bivvy up and keep a low profile, fortunately we were never caught.
Big beds of baits always worked well, particles, boilies, pellets and tigers. The last time I was there I met a Spanish guy who was Sponsered by Mainline and he had taken 200kg of boilies for a long weekend