Normally you'd run the "planks" lengthwise. Won't make it any easier but will look better. Measure overall width carefully and cut the started row of planks as needed so you don't end up with the last row being a narrow length.
I installed laminate planks in a previous TT and the cabinetry wasn't even close to being in a straight line at the floor. I used some green painters tape and scribed a line on the laminate then cut it with a jigsaw to get an even gap. I made our gap about 3/16" and used some wood 3/8" thick x 1-1/2" tall as a baseboard to cover the gap and stained & varathaned it at cabinetry and painted it an almond color against luan paneling.
You'll want to allow for expansion/contraction throughout and movement anywhere that it can get hung up like at entry door threshold, dinette table flanges, toilet, etc.
FWIW, you'll be working on hands and knees in a cramped area and may benefit from knee pads and a bottle of Tylenol. :(