Do you know of any tri shorts that have leg hems more like cycling shorts - 8" or longer?
I'm pretty sure TYR makes a short with an 8" inseam (model name might be Splice), and SkirtSports also has "multi-sport" shorts with an 8-inch inseam. And I've seen some Orca shorts in a local store that look longer than most tri-shorts, but I don't know any specifics about those.

Men's tri-shorts also tend to have longer inseams. Depending how you're shaped, those may work for you.