My far from expert take:
you have essentially four options:
1)One of the 'chain' trusts, e.g. silencershop's.
2)One drafted by a local attorney with deep NFA knowledge
3)One drafted by a local attorney without deep NFA knowledge
4)A DIY from one of the Quickie Trust legal books.
All can work. #4 is cheapest, and I know people who are happy with theirs. #2 is the most expensive, but probably safest, and potentially customizable to your exact situation. #1 is mid-priced and seems, to me, likely to be fairly safe. You hope the vendors did the basic homework, and have been selling a lot of them. If they made an oopsie, hopefully you're not the lone guy on the hot seat.
#3, to me, seems kind of iffy. It runs the risk of being as expensive as #2 but less safe than anything but #4.
FWIW, I did #2. My first try was one of the chain arrangements with a local attorney as part of a network. I called the designated local guy for my state, during normal business hours, and he seemed tipsy if not plastered (in fairness, it was shortly before Xmas; maybe he was at the office party). Anyway, I wasn't getting the warm fuzzies about the answers I was getting. I found a local specialist, who was a big NFA owner personally, so I figured he was likely to have the issues figured out. Of course, the one in your area (or mine; this was a few years ago) is probably perfectly competent; you could call and see what you think.
In truth, I think any of the 4 ways are reasonable options. Do whatever it takes to make you comfortable.