Solar System scale activity

In 2014-05, I was asked by Sagamore second grade teacher Ms. Quinn to help do something for the first grade and kindergarteners on Sagamore Space Day. I'd like to do what I proposed back in January, of imagining the real scale of the solor system, riffing off of, "How Big is the Solar System? | It's Okay to be Smart | PBS Digital Studios - YouTube".

The longest length of the Sagamore field is 480 ft

I'm using an online solar system scale calculator to see what our solar system model can look like. Although the video serves science education by using metric units, I wonder if we should use US customary units instead? Using the scale chosen in the video, 1,264,000,000:1 (calculated from the video's stated 110 cm (4.3 inch) grapefruit = 1.39 million kilometer sun)!, we can comfortably get out to Saturn at 370′. A 5.5′ sun gets us Saturn at 470′ (the length of our field) and a scale of 1,600,200,000:1 , but I think I'll stick with their scale because they give us good size references (e.g. Mercury is only the width of just 4 human hairs).