There are many types of hard dinks...
...including nesting dinks like Danny Greene's designs, which can be cheaply built using the stitch & glue method. His TWO BITS design ends up being 4' x 5' x 1.5' (approx) and that will fit on very small boats yet carry 3 crew when being rowed. But it surely will be hard to see around if stowed on the cabin top. And then there are hard dinks used for extended cruising on micro-cruisers of 14' LOA or so, and which carry 2 crew and groceries when 'unfolded'. Of course, these are used on boats with such shoal draft that one rarely uses them like most of us use our dinks, in agitated anchorages some distance from shore.How small a boat? How long is a piece of string...?Jack