Here's a solution that I've employed over the years:
There is a company called Eagle One
www.eagleonegolf.com that has all sorts of turf and equipment supplies.
In the past they have offered a "test tube" like divot bottle...slightly larger than the circumference of a silver dollar, and about a foot long. When filled with divot mix it weighs about a pound, maybe 1.5 pounds. It is a perfect accessory to slip into the drink pocket or ball pocket of a typical stand bag.
Unfortunately--looking at the website just now, I didn't see this porduct offered, but perhaps another company is offering something similar?