So, my understanding at present is that the reason they have listed just 4 species is that by doing so, the economic impact is under the limit that would require a Congressional vote.

This leaves them open to do the same thing with the remaining species...as separate additions, rather than adding them all at once.
A grocery cart full of food is a lot more money than just one bag of apples, even if you come back 2 hours later and buy a bag of oranges, and then 2 hours later and buy a steak....
The total comes out to the same, but it's calculated separately. This is the loophole they are using.

I think what the reptile community really needs to do is get better numbers, harder numbers, and get them very quickly. If we can prove that the economic impact from banning any one of the remaining species is high enough to warrant a vote, then we may be able to prevent them from ever listing that species.

I also think that getting better numbers may be one way to take them to court over the Burmese, provided we can legitimately get that figure high enough.

A lot of penny counting will have to be involved--from the cost of the rats fed to a snake, to the bedding, to what a shelter would have to pay for an animal abandoned because its owner had to move out of State.

Perhaps this simply isn't feasible, but it is one legitimate avenue to consider. There aren't a whole lot of options here.