Originally Posted by bfolens
Something like a harness? I am pretty sure I have seen something on the web but not able to put my hand on.
New owner, researching the same. I've found two options on this forum by google-searching "Sportsmobile four point seat belt". One is made by EZ-ON (model 86Y) that uses the existing lap belts (shoulder belts have loops which slide over the existing lap belt ends before you buckle), costs about $90, and requires only mounting the shoulder/3rd point on the cross-bar behind the bench. My reading tells me it's the less-intrusive option if you also use your bench as a bed (less to deal with when folding the bed).
The other, cheaper, options is currently on sale for about $60, and you mount both the lap and shoulder belts. Made by Wesco performance. https://www.wescoperformance.com/4posebepubub.html
thread here: http://www.sportsmobileforum.com/for...eat-17442.html