If walking around to the “Front” X axis that the gantry spans truly is not an option for your situation, then, personally, for a quarter sheet 2’ x 4’ usable cutting area or smaller, I would stray from the yellow brick road recommended path to success.
Personally, for the sake of maximizing joy and enabling easy machine usage in your situation, I’d go with “Landscape” mode, and accept the slower feed-rates that comes with that… I don’t know how much slower in mm/s or %, maybe someone has numbers?
Some context, I’ve tried both layouts…
I like my current recommended by default “Portrait” mode quarter sheet LR4 layout. But, I couldn’t imagine trying to use it without easy access to the “Front” where the Router bit needs to be swapped, probed, clamping/screwing, closely observing cuts, etc… I’m average height without Orangutans arms, so, others more genetically gifted might feel differently. My CNC bench is on swivel casters with brakes. I’m not getting younger/fitter, am trying get all my heavy tools onto wheels/swivel-casters, that’s another topic… Mentioning incase casters could help in your situation.
I do miss my “Landscape” mode LR3 layout, which seems to be working out fine for @Tokoloshe (a seasoned V1E builder, so others’ results may vary…)