Anyone know where you can get a 70x35 1/2 topper for use in a single on the 2022 320 S?

CCC

Most twins measure 75 x 38.

VictoriaP

Mattress Insider makes custom size toppers that many here have used. Others have bought regular foam toppers and simply cut them to size.

Bayliss

@CCC, ditto what @VictoriaP wrote.  This discussion thread may be informative:

https://tab-rv.vanillacommunity.com/discussion/10774/mattress-topper-suggestions-please

fstop32

The "MyPillow" company will make custom sized toppers also.

Tabnero

Mattress insider has a 35x72 standard size you can order

SLJ

We just use these https://amzn.to/37TP17O