I've recently become interested in making my own tactical gear for similar reasons.
I might be willing to take a stab at something simple like a
split-front MAV in yellow (might have to be yellow w/ black webbing) eventually - on strictly an amateur basis.
I wonder if there is a huge un-met demand out there for high-vis tactical gear. It seems that if someone tested the market and there turned out to be serious demand, the big names could jump right in simply by adding some other colors to their fabric inventory.