If you don’t have a heated place to store your barrels over winter I would use your higher rate of carrier 40 to 50 gallons and just get at least part of it out there. What are you using for spray nozzles? A solid stream type nozzel at 40 to 50 gallons would hopefully make it through most of the residue and to the soil surface. The weather rarely gives us perfect conditions, just don’t let perfection get in the way of good enough.

Both Rejuvenate and Sea Shield labels say that crystalation and settling can occur below 35 degrees. So I would be leery of storage in a non heated place. Seems like once Rejuvenate settles it takes a lot of mixing to get it agitated enough to be usable again.

Good luck in getting your fall primer out there. I only got about 1/6 of my planned fall primer out before the snow and ground surface froze. So you are not alone.