Crawler IP range for non-production sites

I saw this in Crawler IP Address or Block but there was no reply.

I'd like to index my non-production site, which sits behind an IP restriction. Could you let me know your crawler IP range(s) so I can whitelist it please?

Nick

Frustratingly Swiftype support have confirmed that this is not possible:

The longer term plan is to provide a crawler for users to run themselves, putting all data into app search (essentially replacing site search), though there isn't a concrete timeline for this I'm afraid.

A stable list of crawler IPs unfortunately isn't something that has been collated at this time.

I will go back to the drawing board.