Awe man! I had everyone else beat until this post lol.
I hauled x6 2x12x16 boards along with x24 2x8x8, box of joist hangers and 8 bags of quick Quick Crete in the bed of a 1999 F150 SuperCab with a 6ft bed.
I had the tailgate up and everything strapped down, it was an hour drive home.
I'm not trying to beat anyone, but...
My B-I-L needed to buy some stockade fencing, and I had the only truck of any kind at all in the family- a 1988 S-10 with extended [but not Crew-] cab and 8 foot bed.
The fencing panels were 8' high by 8' long, and we loaded the truck so full of them [by alternating the way that they faced in pairs so that the cross rails meshed together] there was no space at all left between them and the wheel humps, then packed Quick-crete bags in front of and behind the wheel humps to add support, finally strapping it all together with 2 HF 1.5" ratchet straps- one high and one low.
We put as many people as we could physically fit into the truck cab as ballast- besides my [then 195#] self, my B-I-l had my S-I-L sitting in his lap, my teenage nephew sat on the center console [it had bucket seats], and 2 of my B-I-L's friends both sat on the fold down jump seats in the cab extension.
Despite [or because of] that, I couldn't get it to go over 17 MPH all the way home [by backstreets where ever possible], and even so, the under-steer was so bad that I could barely make the turns necessary to get there.
A couple years later, we put a full sized refrigerator in the back for my other B-I-L, [standing up, of course] well-strapped in, but then couldn't get it to go over 45 MPH [or 50 down hills] on the highway because of the sail effect of the refrig extending approx 2 feet or so above the cab.
