Howdy,
I'll try to address all your questions.
I have an AMD-65 and you can access the trigger when folded. My one concern for you in paticular is if you're planning on holding your arm under the handguard since you can't grab the forward grip, that thing is a frying pan. if you're just using your arm under the grip, it would be fine. But the metal around that forward grip gets hot after about 50 rounds.
I also have a converted Saiga. I don't know what the heck that person is talking about with the trigger not working. When you convert a Saiga, you replace the weird "sporting" trigger with a regular AK trigger...and it doesn't have any parts to keep it from firing when folded.
My ACE sidefolder on my Saiga is specifically bent to be out of the way of the trigger and it could be accessed from either side with the stock folded.
The reason the side folder AR stock only works for one shot in the AR needs that buffer tube in place to help the bolt move properly. I could fire my AKs folded....I just don't bother because its pretty hard to be very accurate past about 20 yards without a stock.
If the AMDs are still cheap, that's a good option. The other thing you could look at are underfolders. I have a century built Polish AKMS and its not a bad little gun. I got mine for around $500, but the only place I can find them in stock is Atlantic Firearms, and they're throwing in a drum magazine, calling it a "package" and raising the price past $600.
If you have any other questions, don't hesitate to ask.