There's nothing wrong with towing with a unibody. These aren't 80's K-cars. Some unibodies are rated for well over 7,000 pounds (Touareg, Grand Cherokee, Ford Transit), and some even require weight distribution for max towing (Ford Explorer/Flex).
The Audi Q5 has more braking power than most half-ton trucks from 15 years ago.
1,047 pounds of payload is better than a high-trim Ram 1500 EcoDiesel.
That said.... The 440 hitch limit is a hard limit. Weight Distribution won't fix that. That hitch limit effectively limits it to trailers under 3,000 pounds. Not only that, the Q5 is NOT APPROVED for use with a weight distributing hitch.
OP - Those Ultra-Light trailers proposed look doable, but only if you don't carry rear seat passengers or much cargo in the trunk, because of how the tongue weight will load the rear axle, especially since you can't use weight distribution. If it's only 2 of you, it might be doable. Family of 4? Probably not.