Not going to say no there isn't.
Most likely you will find what you seek in extremely small trailers like a TAB.
In reality, RVs are designed and built for a wide audience, a single twin bed is not a wide audience.
You are going to find multiple twins, one full size and one twin one queen and several twins and so on in larger trailers.
As far as a bed running the full length of the wall, might find something like that in a "lite" trailer. Lite trailers are a bit more narrow in width than standard trailers.
Typically in RVs the bed length IS short and finding any bed in standard home lengths is almost impossible.
Even the so called twin beds are not as wide as your home bed, so a FULL size bed is a bit closer to what you seek.
Home twin is about 40" wide, RV twins are on the order of 32-34 wide or about what a home couch depth is.
Keep in mind, many trailers the dinette table drops to make a bed, that also is counted as a bed, in your case, ignore the table bed..