Using RTH at a distance of 20m or less causes craft to land immediately. This can be problematic for landing in situations where, except very near the Home Point, water, terrain, trees, buildings, etc., are unsuitable landing sites. Is there anyway to change this parameter to allow RTH to bring the craft near to the set Home Point? I know one can always terminate RTH and fly by stick but at 20m, lighting, poorer vision, or some other unforeseen condition may make it difficult to gain proper rudder and bring it in.

That's how it operates and it cannot be set to anything else.
BUT, if flying within 20m, there's really no reason to ever get the aircraft into RTH mode.
If you lose orientation panic and want to press RTH, instead just let go of the sticks and walk over to the aircraft to regain orientation.

The only time anyone would be using RTH at a distance of less than 60 feet would be newbies trying it out and not flying far enough away.