A method of manufacture of vehicular trailers comprised of: a suspension 
system (A) slidably attached to a 
load bearing frame structure (B) enabling said 
load bearing frame structure (B) to horizontally pass over the 
vertical axis of said suspension 
system (A); a means (C) to apply force so as to cause or tend to cause motion toward the source of the force; a rotatable means (D) allowing said 
load bearing frame structure (B) to roll along a surface; a floating link variable height hitch 
assembly (E) providing a means for the tongue of the trailer to move vertically and past the 
horizontal axis of a generic hitch 
receiver (10d). The combined dynamics of (A),(B),(C), and (D) enabling said load bearing frame structure (B) to deploy or retrieve a load at or beneath a 
ground plane of the 
towing vehicle; an asymmetrical design of said floating link adjustable hitch 
assembly providing a means to enable 
adaptation to any height 
towing vehicle (120) by rotation in the generic hitch 
receiver (10d) 180°; in the case of the preferred embodiment hereof a boat trailer combination (200) providing a means to launch and retrieve a boat into or out of the water at or below the 
ground plane of the 
towing vehicle without a launching ramp or extraneous apparatus and without water 
contamination; in the case of an additional embodiment hereof a 
multiple use vehicular trailer providing a means to deploy to or retrieve to or from a 
ground plane equal to or beneath that of the towing vehicle.