It looks like a tight fit for your fenders. I hope it all works out well for you.

I think you've hit it. A big company like Schwinn can order special purpose tires for a new line of bikes they're building, but small companies, and individuals deal with what is available.

I remember my 16x3 (12" rim) moped tires were a bit of a pain to mount, but my Schwinn rims are quite wide, so I got them on ok. Something was also funky with the valve. Maybe I located it after mounting too.

I think it has taken at least a half century of people being dissatisfied with flat tires on 700c 23/25mm tires for the industry to finally take note, and now everyone is making a flat resistant tire.

The cargo bike industry is rapidly growing, so perhaps people will take notice. It may already be diverging into lightweght cargo bikes, heavyweight cargo bikes, and long distance (high efficiency) and short distance (low efficiency) bikes, each with different needs. The electric cargo bikes will also change the perspective of the industry.

I do like aluminum rims. Recently I snagged a couple of SunRims DoubleWide rims that will go into a future cargo build (I hope). They appear to be a very sturdy rim.

Anyway, I hope all works out for you.