My kid is nowhere near as tardy as Rev or in need of such intense 24/7 care, but we get 26, 8 hour days worth of respite care per year.
That's 8 and a half whole days.
We aren't in USA but I I'll bet she qualifies for some type of paid for respite as a full time carer of a tard baby.
Her Mom is probably going to be the one getting paid to care for her, but if necessary, Rev could probably get a 'free' place in a respite centre for a week while the rest of them went on a cruise.
That's literally what respite care is for.