Yes, but every trailer has the utilities in a different part of it and all of the spaces have the electric, water and sump is in the back of the space. If he has a 5th wheel, that will be a long way from the bathroom to the sump since those bathrooms are in close to the front.....
We have stayed at Playa Bonita many times in a 40 foot class A. If you are beach front, and park so that your front window is facing the water, you should be able to reach the electrical connection with the 25 feet of cord that I'm assuming you have. However, sewer maybe a different situation depending on the site. For half the beach front sites the sewer connection is on the other side. That means you would need at least 40 to 45 feet of sewer hose. If you don't want the view out your front window then it should be no problem. The in line spaces should be no problem as the hook ups are at the back. The electrical there is 30 AMP, but they will wire in a 50 amp for you for a few dollars.
Thanks Vegascpl ... we will be in an interior site I believe as there were no beach front available... any other Puerto Penasco tips will be appreciated.. like is it walkable to a grocery store as we will be leaving our car in Ajo AZ