There is no official or unofficial SHR mapset that is publicly available. The guidebook does include maps but they are inadequate for field use: they are black & white and printed on standard paper stock, and the scale is not ideal for technical navigation. (I believe that Roper included these maps to make the route less abstract for guidebook readers who may not yet have a mapset.)
Without a publicly available mapset, aspiring SHR hikers have had to assemble their own. This consumes time & energy that could be spent on other aspects of trip prep, and it can be frustrating trying to piece together the perfect mapset. To reduce this barrier to entry, I have made my SHR mapset available for purchase on CD-ROM.
What is a "perfect SHR mapset"? For me, it included two map series: one set of technical maps that permit safe and efficient navigation; and one set of overview maps that offer area context and emergency exit routes, which are hopefully unnecessary but which are wise to have on hand. Also, the mapset should be efficient, i.e. I don't want to carry or pay for mapped areas that are irrelevant to my route. And I also prefer to keep the total cost of the mapset to a minimum.
Assembling a mapset can be done using paper maps or mapping software, or a combination of both. Paper maps are time-efficient but they have several pitfalls: large portions of the maps are often inapplicable to the route; they are not conducive to quick referencing because of their large paper size and their numerous folds; and it seems that trekking routes have an uncanny habit of straddling map edges and bouncing back and forth between maps. Mapping software allows for a more perfect mapset, but it's a more time consuming process: the mapset must be created from scratch and then printed.
A paper SHR mapset could be pieced together using maps from at least three map publishers:
US Geological Service. The 7.5-minute topos, which have a scale of 1:24,000, are ideal for the "technical mapset." And the 30x60 minute maps, which have a scale of 1:100,000 are ideal for the "overview mapset." But the cost of this mapset is almost prohibitive: the 195-mile SHR would require 30-40 7.5-minute maps at $6 each (and probably another 10 maps would be very helpful), and then probably 10 30x60 minute maps at $7 each.
National Geographic Trails Illustrated. The entire SHR could be covered with just three TI maps (#205, #206, and #809), but they are not ideally suited for technical navigation -- the scale is 1:80,000 for the Sequoia-Kings Canyon and Yosemite National Park maps and 1:63,360 for the Mammoth Lakes map, the latter of which would be marginally adequate. TI also makes two 1:40,000 maps (#308 and #309) that cover about one-quarter of the SHR; they should be adequate for technical sections but they obviously would need to be supplemented with other technical maps in order to cover the entire SHR corridor.
Tom Harrison. This California mapping company produces about 10 maps for the High Sierra. The most detailed maps have a scale of 1:40,000 and 80-foot contour lines. These detailed maps are not available for the entire SHR corridor, so some of their 1:63,000 maps would also be needed. The least detailed maps have a scale of 1:125,000 and 200-foot contour lines.
If the three paragraphs above did not make it clear, assembling a SHR paper mapset can be a frustration-causing puzzle. And, regardless of how hard one tries, a perfect mapset can never be obtained because these general area maps are not completely relevant to the SHR.
A perfect mapset can be created with one of several electronic mapping programs, which are available online or as desktop software. But this process is time consuming: the mapset must be created, exported as printable files (e.g. JPG's), and then printed. I usually have my maps printed professionally, which assures that the fine detail is preserved and that they maps are resistant to bleeding/smudging and flaking. I have used consumer-grade printers for maps before but I have never been pleased with the results: the quality is disappointing and the process is slow; the cost savings are minor after accounting for map paper, ink, and time.
I have a lot of experience with TOPO!, which has some quirks but which is functional. I can't comment on the MapTech or iGage packages. I have used TopoZone.com and I cannot imagine trying to develop a mapset with it. There are free online map databases from TerraServer and numerous universities and state agencies, but I have intentionally avoided them -- again, I think it would be frustrating and time-consuming to develop a comprehensive mapset with them.
For the SHR, I created the "perfect mapset" that I outlined above. I printed both mapsets in color on 11x17 double-sided sheets,. The technical mapset was at a scale of about 1:24,000 and the overview maps at 1:100,000. Because the largest export size offered by TOPO! is 8.5x11, I had to export the maps at a scale of ~1:29,000. Buzz and I were both extremely pleased with the results.