How concerned are you about using a documented shelter?
The Diamond Shelter is ... accepted ... at most events, but documentation for that specific way of setting up tarp is pretty lacking. Only ONE painting has ever been presented as "documentation" for it, and the "interpretation" of the tarp in it is very much in question. Most of the details of that tarp are lost in the dark behind the voyageurs that are the center of the action - repairing a birch bark canoe before them by torch light. The painting only shows one pole and one corner of the tarp behind them. It more likely is a tarp strechted up and over another canoe behind them. Plus ... big detail ... it is of VOYAGEURS up around the Great Lakes and in Canada!
So documentation for the "diamond shelter" is ... somewhat lacking. But it is "accepted" at most events.
I have used a diamond shelter for most of 3 decades. They are GREAT. A simple/quick shelter for one or two people. And fairly easy to pack along. But I now personally restrict where I use mine. I more often use a simple tarp set up as a straight leanto, or a wedge tent where concerns about historical accuracy are a higher priority.
Did people ever use that specific configuration in the past? Probably. But they did not include it in paintings/drawings, nor describe it in writing. Yet in these modern times, it has almost become the "standard issue" tent for people who call themselves "longhunters". Even some of the "hard core" organizations that require 2 or 3 or more pieces of documentation for all their gear still "accept" it. Kind of funny how that works ...
A simple square/rectangular tarp set up as a simple slant roof "leanto" are documented most everywhere and when. And so are Wedge tents - in assorted sizes depending upon time period and military or civilian usage. And wall tents and marquee tents get more and more specific to time periods, cultures, and areas in the "details" of their size/shape/style.
Of course, these are but my humble ramblings, and best used in conjunction with your own research.
Mikey - yee ol' grumpy German blacksmith out in the Hinterlands
- who has loved his Diamond shelter for several decades, but can't document it.