Hello,
Sorry, I misread the question.

I don't know if it is possible to achieve it with NEX 7 as I don't have one, but if it would be, that would be the solution.
I don't use IR triggering as it is slow and unreliable, but with NEX7 you don't have a lot of options. You can hack the shutter button or use a servo, but both are workarrounds.
With Sony A5000, A5100, A6000 you can use direct wire trigger and 1s triggering is no issue.
Best regards,
Alex