Massively long jobs causing NGINX to "Gateway not responding"

I have written an accounting system for a rental business which is currently based on Laravel 4.2.

At the end of each month there is a month-end procedure that besides anything else creates all of the creditor remittance advices and owner statements as PDFs using DOMPDF.

The problem I have is that this process is really slow and intensive and as a result the server is timing out. My procedure operates from a single page which is updated via AJAX. I could quite easily change this to a multi-blade process, but I do not think that would necessarily resolve this issue as the timeout is server side.

I have tried issuing the PDF generator via jobs (artisan queues - one per PDF), but the amount of data is too big for the queue to handle in one particular creditors case (their statement is 24 pages long). So instead I tried to step back one layer and make the whole statement generation process a queue. This kind of works, but then I get no feed back to the user telling them when that process is completed.

So what I am looking for is a way of initiating and getting progress back from really really long jobs or an alternative solution. Any suggestions are welcomed.

Thanks in advance