Whenever I paint and base units with firing musket poses, I place the firing figures as far back on the stand as I can so that the musket and bayonet do not protrude beyond the edge of the base. All the better to protect the figures from rough handling, and it ensures that if I line up the stands in columns, then one stand is not stabbing the stand in front of it in the back.
Then, to present the illusion that I have two ranks, I place some of the figures who are not firing in the front rank, leaving spacing for the firing poses to fire without hitting the guy in front of them. I find that I don't need to have the same number of figures in both the front and rear ranks to achieve the illusion of a two rank line.
As for the fringe, it is just a matter of painting the fringe a lighter color than the main hunting shirt color so as to provide some visual contrast. I paint a darker shade of the main uniform color on the fringe and then use a highlight of that color, painting little dots or hash marks, to make the fringe stand out.
The purple hunting shirts started life as the 4th Independent Company of the Maryland State forces as I had intended for this to be a Maryland battalion (it still might be designated as such, yet). However, using Lefferts as a source, it appears that many of the Maryland regiments might have had regular coats during the 1777 period, so I switched the unit over to one of the Pennsylvania regiments of the Continental line.
I would imagine that hunting shirt colors could vary by company, or there could be a mix of colors across each company within the regiment.
Most of this is just artistic license on my part in order to enhance the appearance of the regiment on the table top.