Timelapse exposure stepping.

I shoot a lot of timelapse and resolve has been great for that, until I started doing day to night (holy grail) sequences. My problem is the sudden step in exposure when my camera changes aperture. The flickering caused by small variations in aperture is easily taken care of with deflicker, but a sudden drop from f4 to f 5.6 is not.
Is there anything that can help with this? The only thing I am aware of is LRTimelapse, which has the perfect solution and only costs £85, but requires Lightroom to work and, apart from this one feature, I’m happy with my non-lightroom setup right now.

I’m on the full version of Davinci on Windows.