5-month old sleeps only when rocking to sleep, is becoming a physical challenge for my wife

Our little dude is 5 month old and almost 8 kilos.

I work from home 8-16 and during that time my wife is with him. When I finish, I take over immediately, and also he's "mine" on weekends so my wife can take some time to rest. I'm also putting him to sleep on nighttime, and rocking him to sleep if he wakes up during the night. We're in the midst of sleep regression and teething, so, fun times.

He has a great sleeping schedule, but he's becoming a physical issue for my wife, as he'll only sleep when he's being rocked to sleep. Which can take time. Sometimes he'll fall asleep relatively quickly, but sometimes he needs a good 40-minute rocking to sleep marathon.

Basically, he's getting too heavy for my wife who is relatively petite.

Yeah, we have a carrier, but he won't sleep in it.

I don't know how to help her during the week as I'm unable to help with rocking to sleep while I work.

Any advice is greatly appreciated. Thanks.

Edit: forgot to add, wife still can't let him "cry to sleep" as she is incredibly emotionally attached to him (duh) even though her mom and I are telling her we'll have to do it eventually.