Can it be estimated when it would actually be beneficial to increase drag in tailwind? Usually the advice for cycling is to try to be as aerodynamic as possible (like, reduce the surface exposed to the air in front of you) in order to decrease drag as it will cost less effort to maintain a given speed. Especially so with headwinds. However I think there might be a point when riding with tailwind where it would actually be beneficial to increase your surface so the tailwind has more effect than the resistance of the air in front of the cyclist and hence actually helps 'pushing' one forward. Is there such a point and is it possible to estimate at roughly what tailwind speed it occurs (let's say on a flat road and other factors all equal)?

Or another way to think of it, in practice: say I have two jackets, one pretty tight and a looser one which tends to form a balloon, would it ever be beneficial to choose the looser one because it increases total surface so the force of tailwind applied to it is larger than the force in the opposite direction created by the resistance to the air in front of me?
A tailwind reduces your relative airspeed and therefor the drag you generate. You can go faster relative to the ground  with the same power output. The only time increasing your profile might be beneficial is if the wind is traveling faster than you are, relative to the ground .... Unless you cycle slowly or the wind is very fast, it's usually not the case. This is cycling, so aerodynamic is mostly about reducing drag, unlike sailing where maximising lift is important.