Yes, I know not specific Toyota related, but at least I know there's decent expertise on here.

My car trailer is suffering from some old age and previous overloading woes & has therefore started to bend
2 things are the problem.
1. it's only got one axle
2. it was built too light for the job its meant for.

The bends are over the axle line (not too much of a concern) & where the A frame meets the bed (a lot more of a worry).
The trailer structure consists of a single large spine down the middle & smaller side frame pieces instead of the normal 2 rails down the side.
This means the main structure is a long way from where the weight of the carried vehicle is.

I'm already aiming to remove & replace the A frame with something more substantial (and will also be adding about 300mm length), and add a 2nd axle, but my question relates more to the new side chassis rails I wish to add.

As its a car trailer, most of the weight is placed on the corners where its tyres are. This weight needs to be transferred to the trailer suspension which is in the middle (length-ways).

Does anyone see any issues with putting the new chassis rails in line with the wheelbase of the car & then having the trailer springs under this?
This will mean that they are further inboard than most trailers have their springs mounted, but means that side transferring of the weight via structural members isn't required (& I can remove some of the now redundant weight from the existing inadequate side structure to bring the trailer weight back down a bit).

I'll post a diagram & pics tonight of the frame layout if this is a little confusing.