The way we build here (not the Burners) the size/width of a bass is determined by the Neck, NOT the Body. Even if it's a bolt-on, the center block or neck running thru the center is what makes it wider or not. The body wings on all BSR models are the same and universal to go on any model, 4, 5, 6 or 7 string. The BT models have the same deal going with the BT wings.
The Burners are basically the same principal as well being that the continuation of the neck determines how wide the bass is overall.
On a BSR or BT wide model we make the 5-wide in 19mm spacing with 10mm nut spacing instead of 9-18mm spacing. The wide model 5-string Bass will be 4mm wider overall then the normal 9-18mm model. A 6-wide will be 5 mm wider between the 18-19mm model as well.
http://www.kensmithbasses.com/options.html .. Scroll down for spacings. The Wide model is not listed there, sorry.