The brake conversation isnt about speed. Even at 25mph when you try to stop for a stop sign/red light the load tries to push the truck. I am positive you are a great driver, everyone on the internet is. But what happens when you are doing your thing poking along at 45mph and some dumbass blind grandma pulls out from her driveway 250' in front of you? Its happened to me and Im sure its happened to you as well. With a railer behind you all kinds of bad joojoo happens there.
The tahoe you had almost certainly weighed more than that F150 which actually helped you out.
Also I would just about bet if you had a 6,000 lb boat (thats a big sucker. My 19' Ranger bass boat with the 150hp Johnson weighed lesss than 2,500lbs) it had surge brakes built into the trailer tonuge. Almost all of them do.
Finally no one is saying your buddy isnt crazy/extreme/hardore enough to put 10,000lbs on that trailer. What I am sayoing is IF he put 10,000lbs on it. The side rails would bend/snap, the tires would pop and axle would be permanently bent.
Think about 10,000 lbs for a second. A stock 1990 Cherokoee weighs 3,100 lbs. Do you think that trailer would hold up if you stacked 3 cherokees on top of it?
I know it wouldnt.
Ive got a home built trailer. The entire outer frame is made out of 3" C channel.It uses 2" C chennel for the cross braces and has 10 of them over 18 ft. When we built it we ran a 3" I beam up the center standing up for tortional stiffness. It has 2 6,000 lb braking axles. I've hauled just over 12,000 lbs on that trailer once and it held it fine, however you could see the metal deflecting slightly under the load and the tires were HOT even at 60psi. Hot enough that we stopped every 40 miles or so and let them cool down to prevent a blow out.
Again I am NOT bashing you. I applaud you wanting to get a trailer and tow rig, God knows it is the best way to enjoy wheeling further destinations. ust dont alwyas jup at the first/cheapest thing you see. Take time to find the RIGHT fit for the application.