The three stats that matter when looking for the Otter are a surveillance over 135, Speed as high as possible to minimize trip time, and a high favor which is only 90 on this build so you wont always get a second loot item.
Range doesn't matter so long as its enough to reach Deep Sea Site 7 and Retrieval has no impact as the otter so far has never given more then 1 in a trip.
So yes its a terrible build for normal missions, but if your after only otters then I still stay it would be perfectly fine for the mission and is a very cheep sub to build.