Why Finding a Western Saddle for Icelandics is so Difficult

Why it is difficult (but not impossible) to get a properly fitting saddle, especially a Western one, for
an Icelandic horse. Below are wither tracings for 8 horses. The top tracing is for:

A. Blessi, my 14.1 hand Icelandic. Note the upside down U-shape which typical for an Icelandic (there are exceptions). His gullet (width of tracing measured 3 inches from top) is 9 1/2 inches.
B Clydesdale 18 hands gullet = 11 inches
C Mustang 15 hands gullet = 6 1/2 inches
D Warmblood 17 hands gullet = 8 inch
E. Quarterhorse 16 hands gullet = 6 3/4
F. Grade pony 10 hands gullet 9.5 inches Blessi's saddle fit him through the shoulders but the saddle was too long on the back
G. Paint stallion 17 hands gullet = 6.5 inches
H. Quarter horse 16 + hands gullet = 6 inches

Most manufacturers for trees used in Western saddles are designing them for A-framed horses like Withers example E. Saddle manufactures may call a tree used that would fit this gullet size semi or full (there is no standard from saddle manufacturer to manufacturer). Blessi would theoretically take a draft horse size Western saddle but the rock, angle of the bars, flatness of the back, etc., would not fit him. Blessi has a custom made Western saddle.

If you are looking for a Western saddle for your Icelandic, Crest Ridge Saddlery explains how to do a 3-D mapping using wire for your horse. You can take this mapping and lay it on top of the saddle to find a few saddles to borrow for fitting.

http://www.crestridgesaddlery.com/build-a-back-map.html
And some people have found off-the-rack Western saddles that fit their Icelandics.