I have basically the same advice to avoid the party days if not doing them. Except for Halloween, it tends to be a pretty low crowd day. When we went on Halloween in 2014 & the day after both were very low. And then 2 yrs ago my sister-in-law & her husband & kids did Halloween and the 3 days after and they loved how low the crowd levels were. So my recommendation would be to do DL on the 31st-3rd (that will be 4 days). For Universal if doing on a weekday you have to get up super early to beat traffic (like leave by 6am, a few min earlier if you can) or sit in standstill traffic from 6:30am-10:30am or leave later to have a shorter day. If you do Universal on a weekend then you can leave a little later and not be stuck in traffic (like until 8-9am). So depending on how early you want to be up you can do Universal on either Sunday or Monday & then do Knotts whatever other day you decide not to do Universal. Then for your 5th Disney day you could do either as a half day on your arrival Saturday (great chance to take in the entertainment, get a taste of the parks) or if you think you would be too tired then do a combo Knotts/Disney day as I hear you can easily come back to Disneyland in the evening after getting a lot accomplished at Knotts. But my vote would be to start off the vacation with Disney on that arrival day if you can & use Knotts as a rest day
Good luck with all the planning & hope you report back or at least come back with any questions you have!