Doesn't change the fact that an unbaffled tanker is inherently less safe than a baffled tanker.
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.