Kicking myself for not waiting for a custom vanity but this is what we’re working with. Concerned about leaving the sides open as this is a kid/guest bathroom and feel the collection of dust and whatnot will drive me nuts. Fabricator did not recommend having the countertop go wall to wall unless the spaces on the side of the cabinet were filled in.

Would you go down the path of cabinet fillers? Would it go all the way to the floor or stop before the lip? And if it goes to the floor, what do you do with the baseboard? Would this need to be done by a carpenter? Having a hard time envisioning it and afraid of compromising the look of the vanity. Appreciate any and all advice!

(Note: Vanity retailer said they don’t have cabinet fillers but will provide matching paint)