Ok that makes more sense. Sorry I misunderstood.

Your W and D are going to sit a few inches from the wall to allow for hookups. In that space you can run a 2 x 4 all the way across to give you a level start. Incorporate it into your ladder frame. Shim it level and scribe your front trim to match the floor. Do this before you put the cabinets on top. Make your cabinets to give you a toe kick.

How will you access the hookups?

Your hookups will need to be on the wall. Your cabinets must work around this.