Looking for a 5th wheel brand that meets these needs:

Personally, I'd find a trailer you like and use a laundromat. That's what I've always done. In order to use the W/D combo you have to use hookups and they take up alot of room you can use for yourself. The smallest trailer I have seen with W/D hookups inside is a 29 foot and to get that you lose nearly all you clothing storage space.

My trailer is wired and plumbed for a W/D, but I opted for the cabinets.