I finally found some time to work on the van a bit.
Build a frame to mount my Thule bike racks to the front hitch. Added a locking hitch pin to keep everything tied down.
Also finally got to fabbing a support for one of the car seats. I built it out of 1X1X.120" wall square tubing. One leg is bolted through the floor to the frame of the van and the other is bolted through the floor and a spreader bar (piece of 2" x 3/16 C channel that is 12" long). It is all secured with 7/16" graded hardware which passes through the tubing and is welded to the tubing.
Everything is designed for a 150lb seat+child combo and 50g of acceleration (basically it will stay together with up to 6000lbs of force applied. It will deform slightly at that load, less than 1/4" deflection, but will not break). 50g is generally considered to be fatal. So if the seat ever does come out, everyone in the van will already be dead.
The red ratchet strap was just for test fit. I will be putting in a strap equal to the frame. The strap snugs the seat against the plywood which rests on the frame. The car seats tether strap will be hooked to a flush mount d-ring in the floor.
The whole thing is overkill. NIHTSA requires ~4000lb break strength on seat belt webbing, bolts and mount points and this probably includes a 1.5x to 2X factor of safety over maximum expected load. I wanted there to be ZERO question in my mind that in the event of an accident anything I built would be the reason one of my kids got hurt.
Also added a carrier basket to the back from Harbor Freight.
Next project is window coverings I think, and installing the table base to convert the seat back to a table. I have everything market out I just need to notch and weld the frame of the van to get it out of the way of the hole I need to cut for the table leg mount.