In a GN trailer, the rear stall works well, while using the front stalls for storage. In a BP trailer, the better loading is which ever stall is directly over the axles. This varies from manufacturer to manufacturer. Some center stalls will be over the axles, some with longer dressing rooms will not be centered. Depending on the trailer's configuration, always using the front stall can drastically increase the tongue weight, whilst only using the rear stall can unload the hitch weight, causing poor tracking.

Gn trailers are not as sensitive to specific loading as BP trailers. Generally a 3H BP trailer will allow you to vary the loading, depending on the number of horses you are carrying. This can allow a very properly weighted trailer, that both tracks well and has a minimal amount of tongue weight. Many people assume a 3H BP trailer will have a higher tongue weight than a 2H BP trailer, while just the opposite is often the case.

My slant trailer has a straight wall which makes the first stall pie shaped.. I use it mostly for a mid tack/mud room but able to use it for a horse if needed... If I haul one horse I usually place it in the 2nd stall...