Hi!
I am attempting to build a workbench as my first woodworking project which has been a pretty difficult experience. I glued up separate segments (2x6s run through a planer). I lined the segments up, and realized that the side faces are not straight enough for a good glue up, and clamping pressure will not be as helpful here. I need to somehow flatten these very well, but am not super sure how to do it.
I have a jointer, but it is 6", and these are 8 ft long and heavy.

I attempted a planer sled, but I don't think I did it correctly. It is getting difficult with the mass of the segments, as my planer is not sturdy enough to not heed to their weight.

I can do a router sled, but I think doing this on 3-4 different segments I'm bound to experience some discrepancies in the angle I flatten it. Since I need to have the rails set to a certain point, and I need to shim the bottom of all of the segments evenly each time I do it. I also don't have a table long enough to fully support the long slabs, so I would need to somehow make this setup on the ground outside if I was to do it, and make it replicable.

I'm considering hand planing at this point, but I am very inexperienced, and not sure how long it would take with the amount of material needed. It's probably a solid quarter inch along a lot of these sections.

Do you have any advice on the best way to go about this?