I know of the Madera Mast in 36mm. I'd like to find a Quamen High Neck, but that search is yielding no results. I am curious if there are others out there with similar reaches (30-36mm) that are top load.

The madera mast is the only one readily available. The S&M enduro had one in 36mm for awhile but its sold out, probably a discontinued line due to the 40mm version. The armour bikes skyscraper was made in 30mm. You could try contacting Yegor here or on e-bay to see if any skyscrapers are left. Otherwise just keep checking everywhere for a second hand enduro or skyscraper. One will pop up eventually, they aren't very old.