This site is your friend!
https://tripcheck.com/Pages/RCMap.asp?curRegion=7Oregon will require chains for the truck and trailer if conditions are bad. If it is bad then you go to the coast and take 101 South, which is much slower and requires a lot more driving effort. Do not get as far South as Grants Pass to make that decision. Hiway 38 through Drain is a lower elevation route to the coast than 97. I add an extra day to my schedule to account for having to go the coast route. In 6 or 7 trips with the trailer I have gone to the coast twice South bound. North bound I have always been able to stay on I-5. Once on April 1st we crossed the Siskiyou's the only day that week that it was not snowing up there.
That old Collins is a heavy trailer and all the grades in Southern Oregon are going to slow you down! Hope the trailer has fresh tires for the trip. You will be well past sunset when you arrive in San Jose, fact is the sun may be coming up again.
Make sure the exhaust brake is working well you will need it. BTW you are facing 60MPH Washington, 55 in Oregon and 55 in California speed limits. I tow at around 58-59 in both Oregon and California, "run with the trucks"! In Washington and Arizona 62-63, and let the trucks fly by in Arizona!
M/S S&T's says 800 miles on I-5 and 892 if you go to the coast on 38. That extra 92 miles in very deceiving. I would say it is going to add 4-6 hours of drive time.
Also what day of the week and hour do you think you will be in the East Bay area???? For the I-5 route S&T's has you take I-680 South in the Bay Area. If you are on the coast route then you are kind of stuck of 880 in the East Bay and that can be a bear depending on day of the week and time.
I believe that you are overly optimistic on the drive hours required. Please post a follow up so we can hear how it worked out. If it was me I would make Rolling Hills Casino in Corning (606 miles) the first day, and just park in the free area. Second day make the delivery and get back North as far as you can, then back home the third day! Or drive straight throw on the way back North.
Drive careful.Chris