Perhaps you could ask the seller directly what the dimensions are. But my best guess ( to be helpfull) from looking at it is I reckon about as long as piece of string plus a smidgeon and 2 poofteenths.. but I could be wrong.. hehe
and for a serious moment.. It does look like the FJR front mudguard could foul with the front wheel stop... Check it all out before bidding.
The profile also looks a bit narrow. I'd be concerned about the bike and trailer all tipping over on an unexpectedly rapid corner. It may also bounce around a lot since there is no suspension. A pair of leaf springs and a modest shock absorber would add a ton of benefit, but she'd still make me nervous.
My question would be, why buy a dedicated trailer that is only useful to haul a motorcycle? You can spend pretty much the same money (maybe a little more) get a flatbed (mine is a 5x10ft) and be able to use it for more things.. I added a wheel chock to the front and some 1/2 eyebolts for tiedowns. Works fine.