There are anaerobes that reduce perchlorates (dissimilatory perchlorate reduction). Lack of moisture is a problem, but there will be some supplied by this sweet potato or whatever we’ve deposited on the planet. If we deposited it somewhere where ice was, there probably exists a region of habitability for a long enough period to induce the potential for microbial adaptation in a certain time frame.

It is hostile to life, but microbes would absolutely have a much better chance of growing there than humans, especially spore formers that could endure cyclic periods of high radiation and lack of water, followed by a very brief almost sublimating thaw, followed by freezing temperatures. That’s just if we didn’t provide more seeding material or more hospitable subterranean environs.

There is a significant (not meaning magnitude, meaning statistically reasonably) non zero chance that microbes are actively already living on the planet, not necessarily introduced by us but very possibly. Microbes have extremophiles in their ranks. Life finds a way.