Best be done on your second run
through and definitely on EASY
difficulty. Upgrade it to the fullest first and then you can spend the rest for everything else if you still need to. Make sure you stock up enough ammo before encountering any boss-fight. Also only equip the Plasma Cutter and nothing else, just to make sure! Other than that quite doable in less than 8h since you already know your way around.
If you have anything else that I should add let me know.
See additional notes by "UberniXi
" in the comment section, cheers for that!