Hey Copycat, I prefer to fit my borders to my quilt like you are describing, but I typically miter if I can so I need the extra length on the ends and I cut them a couple inches larger than necessary, just in case. Without the miters especially, cutting both sides the same helps keep the finished quilt more true to measurements.
I find working on my ironing board (especially with a baby quilt) to be good place. I press in place the border right side up and since I am a believer in pinning and open seams, I then press the top in place with the right side down and I pin every leading seam edge and/or every 2" or so. I know many quilters who barely pin at all and who get wonderful results, but that's not me.
I am in a temporary month-to-month rental while we get some things done at the new house. Went into the room with the fabric totes and opened up the the plastic storage drawers but haven't found my portable sewing kit yet. Got a little overwhelmed with everything and backed out. Most of the stuff was packed back in 2022, moved into a pod, out of the pod and into storage, then into a truck and then unloaded. Hopefully by next VQW I'll have my sewing studio unpacked and be able to find things. But first, the upstairs bedroom wood floors need to be refinished and the downstairs sewing room needs a couple of closets built for storing all of those totes and such.