They are not enough less safe to not use them in this application. Baffles make no difference in a full load and the OP will only be at a partial load for a very short period of time when offloading. Milk truck are probably one of the best options for the OP. They are made of SS, readily available and have a large capacity.
If baffle are that big of a deal there are other ways to baffle a tank, like baffle balls.
I've driven milk tanker/truck for 20 yrs(note my user name). I've run a 4200 gal, 5000 gal truck mounted tanks, one open tank, no baffles. Now i haul a 8200 gal tractor trailer. Tank is two compartment, 4100 gal each. No baffles. It takes about 10 farms to fill my trailer. I know all about the slosh factor( surge), easy to get used to.
These tankers are not cheap, but it would be my first choice, anything else will rot out quickly. Looking at the amount of brine they are using, tanker trailer would almost be a must. Manpower costs would be high with anything smaller. just my .02 cents.
Experiment with dry flake as noted before. I've used it on my driveway, works good, but it's only 650ft, not 34 miles. You would need
tons of it. Than you're into storage costs( +permits?), whether its bulk or bag. But might work. You have about $24,000 to $32,000 in doing now. Might find with increased labor/equipment costs doing it yourself, but it's worth looking into. Good Luck.