Having said that I would like to assist in finding you a reasonable solution. Is it mandatory your application require a thermal break stile threshold? If it does we may need to get very creative as to how we construct a solution meaning you may be able to take individual salad pieces of aluminum that are 1/4” thick that would have ball flutes cut lengthwise in them and install it down to the floor in multiple pieces and I would separate those pieces by 1/4” thick neoprene or some other non conducting material. If you do not require a thermal break solution you might simply look into the same concept above where it is a solid aluminum plate just cut to the proper with your application requires.
There are thresholds that are rated for light vehicular traffic and a prime example of that would be the Reese HD5A Saddle Threshold - Mill Finish Aluminum as seen here:
Click Here
but as you can tell it's not nearly the width of the original requested item.