This makes sense. appreciate your detail here. Many ways to hit the end result.Im talking about using the hi lift as a come along to pull the hook parallel to the ground to bend the frame section there down a few mm to be able to slide the bumper in that c channel of the frame. You arent lifting the truck up. The e brake, someone holding the brakes in the cab, or chocking the wheels is to try to keep the truck from sliding across the ground when using the jack as a comealong to pull the vehicle towards a rigid object laterally. When I installed my front bumper i had to use a 4lb hammer and a hi lift in a similar way to open up the front of my frame a few mm or so to slide my bumper in between the frame rails. Its pretty common, and Im definitely not the first person to do this. I just linked 4 examples. Im not talking about completely straightening a frame, OP mentioned he is just trying to slide the frame support rails of an after market bumper through there. The impact to the hook bent the lower part of the frame up less than half an inch.
Not really sure why my touch grass comment got deleted, based on the 10 or so un answered comments, dude definitely does in fact need to go out side and touch grass. aka get a breath of fresh air away from the computer screen. Im confused if i need to post it 10 times or not, or if this is indeed a tech forum