My trailer tent top has a base size of 7'3" x 5'8". I am looking at getting a high sided off road trailer built for it, coz unless i buy from Sydney, the pre-fabricated ones are around Melbourne are 6x4 or 7x4.
I reckon I need a 7x5 for a tent top that is 5'8" wide, otherwise i'll have 9" overhang either side. Seems too much, as i'll be having a hinged, side lifting top that i can lift to access stuff underneath
One seller, a guy who only does 4' wide, insists that I need a 4' wide trailer, as the trailer top should go out level with the guards. Most i have seen aren't like this, so i get the idea he is saying that coz that is all he sells.
So.....the Q eventually..

What is the 'ideal' trailer width for a tent top of my dimensions? Is it one of those 'length of string arguements.? I think wide overhang looks ugly, and i assume it is more prone to damage hanging out wider. However, if it is necessary, so be it.
Any opinions? How far do yours overhang sides?
Cheers.

Oh, and if anyone has one for sale, or knows of a good one, let me know

I think you have just about answered your question here.

I think it also depends on where you plan to take the trailer. If it is a highway cruiser it can certainly be wider without risk of damage than a trailer that you drag through wooded mountain country and tight bush tracks.

The ideal trailer would have the same track width as your tow car. The tent top whilst it can overhang the sides would have to at least stay within the track width to reduce the opportunities for damage.
The width will also depend on the size mattress you want to fit.

Oh - my trailer top probably hangs out about 8cm each side and fits flush front and rear. I have a double mattress but could fit a queen.