I’ve made two airseats, one with no dog bone pillow and the other with. I found that the pillow was more of a hassle in the assembly process and wasn’t any more or less comfortable then the airseat without. If I were you, I’d ditch the dogbone and just use a tube given the shape of the Viscount saddle.
I’ve found what works best for me is to tape the 12" innertube to the saddle using duct tape. Once you get the tube shaped and taped exactly the way you want it, use a razor blade to cut the duct tape about 1 inch below the tube. Remove the tube from the saddle, then wrap the tube with duct tape to help it maintain the proper shape. Deflate the tube slightly, install the cover and re-inflate the tube to the proper firmness
You can also use a few strips of tape to help hold the tube in place on the saddle before you install the cover to be sure that it doesn’t slip
i might as well mention the only bad thing about the duct tape method too.the bad side is when the tube goes bad,its not possible to patch it and requires buying and taping a new one.this is another reason to have the foam on top.if the tube blows without the foam in there its a long painful ride back to where-ever.
i just hope the KH seats get lighter and stonger some day.air seats while comfy,can be a pain in just about every way except your ay ess ess.