[SCOTI]

I've just notched them in the past w/o boxing. Of course, boxing it in doesn't hurt but my thought is it wasn't beneficial.

The location notched is closer to the bed wall & behind the corner of the tub. That area isn't going to see the weight/forces the center of the floor would. They're not capped @ the ends so capping that local area isn't adding to the weight capacity since the strength is in the height of the channel.

The only reinforcement I've done is for the center (when it's notched for differential clearance). I will put in thicker pieces of angle parallel to the notched cross sill above the differential. They get spaced far enough away so they clear while providing support as close as possible to the notched area.

Although it's newer so not the exact same issues as a Square, I'll be doing my 99 CC SWB OBS bed in the near future & will get some pics since I know it will need it done.