My guess the base model lacks the hitch and sway control logic. Hence no official tow rating.
Wheel base length, vehicle weight and load rating for tongue weight tie into the generic max rated tow weight.
Though Subaru learned that cooling capacity is a must if they want to rate their cars to tow.
5000lbs max does not mean you get a 5000lb boat or RV and all is good. It means that it can safely drag 5000lbs across town, not across the US and over the Rockies. I’ve had two 5000lb rated trucks a Land Cruiser and a Sequoia. They were fine with anything up to about 2800lbs then you started to see negatives going heavier. Dragging an RV with either over a long distance you tend to learn to keep it light for sure at or under 3k. Or your wanting a heavier tow rig after the first 500 miles, or a lighter trailer.
But dragging the 5000lb ski boat 20min to the lake is fine and tolerable.
The Ascent will be no different. If your looking to do long RV hauls you wont be happy pulling 3000+ lbs it wont be a great experience. But it will be perfectly fine dragging the 5k ski boat across town to the Lake.
...possibly to be found in the options catalog for the factory hitch?.
