I expect you will draw a blank on that, so I’ve made one.
Installation instructions are as per the previous link.
This plug-in is totally new, so you have just volunteered to be the official tester for it 
First rule of testing: Don’t work on anything important without a good backup.
I think the controls should be fairly self explanatory, but do ask if you have questions.
Some of the results may seem surprising.
I think the “linear” transition tends to sound better with the low pass filter and the “exponential” transition better with the high pass filter, but let me know what you think.
I’ve not tried doing a cross-fade with it, but I’d guess it will sound quite weird.
For a “fade in”, use either “Low Pass” and “Low to High” or “High Pass” and “High to Low”. For “fade out”, it’s the other two combinations.
filterfade.ny (1.36 KB)