Your rendering of what you are planning is ALOT more visually pleasing then the EBay rig. Here's what I think your drawing has over his...
1. His top is awful, looks like a bubble, and the rear window is way too large.
2. His bed is too low- makes it look longer than it really is.
3. His fender flares are too short, again accentuating the looong bed.
4. Jeff- in your drawing, isn't your bed -to scale- shorter than his?
5. Your spare tire and wood panels break up the plain look of the bed.
6. His bed is smooth all the way down, like a cheap dump trailer.
7. His wheel/tire combo is not visually pleasing, and I think too small too.
I would try some "kitbashing"- remember building models when you were a kid? Get a Wrangler, a 50 Chev, and maybe a Willys P/U model and build, in scale, what you're going for.
Suggestion- I just sold a trailer made from 50 Chev shortbed. It was really shallow. You might want to consider scratch-building a bed, or using the 50 Chev bed for a starting point. Your drawing shows your bed sitting on top of the frame, with filler panels masking the frame. His bed is smooth all the way down, which I think makes it look quite awkward.
Ok...my "Paint" skills suck...but I think the top plays a huge factor- check it out...