One property of ailerons' hinges pivot point located at or close to the upper surface is differential increase or reduction of local wing chord.

Deflecting aileron up roughly won't change the local chord, while deflecting it down reduces the local chord noticeably. This geometrical property helps fighting adverse yaw.

Also that gap below the hinges creates more or less drag depending on deflection direction : deflected down, gap's drag is reduced, deflected up gap's drag is higher.

This also helps fighting adverse yaw.

In this upper located hinge position, regarding shroud and linkage location, and assuming equivalent moment arm therfore aileron's horn length,
shroud will be smaller if placed below the wing, and larger (more drag) if placed above.

One property of ailerons' hinges pivot point located at or close to the upper surface is differential increase or reduction of local wing chord.

Deflecting aileron up roughly won't change the local chord, while deflecting it down reduces the local chord noticeably. This geometrical property helps fighting adverse yaw.

Also that gap below the hinges creates more or less drag depending on deflection direction : deflected down, gap's drag is reduced, deflected up gap's drag is higher.

This also helps fighting adverse yaw.

In this upper located hinge position, regarding shroud and linkage location, and assuming equivalent moment arm therfore aileron's horn length,
shroud will be smaller if placed below the wing, and larger (more drag) if placed above.

Edit:

As a side note, since OP mentions unmanned rc plane whose goal is endurance flight, why not consider having a clean wing with no ailerons, and rely solely on two control axis, yaw and pitch.

2 axis controlled airplanes, if designed with adequate dihedral or swept back wings, can handle any kind of flight conditions, and provide quite high induced roll rates.

One property of ailerons' hinges pivot point located at or close to the upper surface is differential increase or reduction of local wing chord.

Deflecting aileron up roughly won't change the local chord, while deflecting it down reduces the local chord noticeably. This geometrical property helps fighting adverse yaw.

Also that gap below the hinges creates more or less drag depending on deflection direction : deflected down, gap's drag is reduced, deflected up gap's drag is higher.

This also helps fighting adverse yaw.

One property of ailerons' hinges pivot point located at or close to the upper surface is differential increase or reduction of local wing chord.

Deflecting aileron up roughly won't change the local chord, while deflecting it down reduces the local chord noticeably. This geometrical property helps fighting adverse yaw.

Also that gap below the hinges creates more or less drag depending on deflection direction : deflected down, gap's drag is reduced, deflected up gap's drag is higher.

This also helps fighting adverse yaw.

In this upper located hinge position, regarding shroud and linkage location, and assuming equivalent moment arm therfore aileron's horn length,
shroud will be smaller if placed below the wing, and larger (more drag) if placed above.