Dumpers (wheeled or tracked) are great as they can carry more and have a much higher top speed than skid steers however there is a point at which they don't make economical sense - and this is one of them. Dumpers also cannot manage the spoil pile so unless you have the room or another machine at the dump site, you will be overrun with one low pile.
A ss in high speed can theoretically cover 100 yds in approx 30 seconds with roundtrip being 1 min. Assuming you can't actually travel that fast, give yourself 1-1/2 or even 2 minutes per roundtrip. Now assuming that you can carry 1/2 yd (of slop) per trip, that is 60 round trips. 60 trips at 2 mins per roundtrip is only 2 hours of shuttling. Not a lot in the scheme of things.
Also, I wouldn't discount a wheeled dumper. Since they articulate, they cause a lot less damage when turning than a tracked or fixed wheeled machine.