Having them sit in the backseat opposite, you is enough protection. He should sleep in different beds for a few days, Isn’t the recommendation three days?

If you only have one bathroom, that is an issue. Here are recommendations from top medical sites.

Having only one bathroom while your husband undergoes Pluvicto (Lu-177) treatment is manageable, but requires strict hygiene and safety protocols for 3 to 7 days after each treatment to prevent radiation exposure from urine and bodily fluids. The primary goal is to minimize your contact with his urine, saliva, and sweat.

Here is what you can do, based on standard radiation safety guidelines:
Immediate Bathroom Safety (Days 1–3)
Sit to Urinate: Your husband must sit down to urinate to prevent splashing.
Double Flush: After using the toilet, close the lid and flush twice.
Clean Surfaces: Immediately wipe the toilet seat and any surfaces he may have touched with disinfecting wipes (e.g., Clorox wipes).
Hand Hygiene: Thoroughly wash hands with soap and water after every bathroom use.
Wear Gloves: Use disposable gloves when cleaning the bathroom or if you need to handle any bodily fluids.
Manage Disposable Items: If he uses incontinence pads or wipes, place them in a separate plastic bag, seal it, and dispose of them in the main trash, or store them separately for a few days if instructed by your team.

Above OHSU recommendations

Personal Precautions
Daily Showers: He should shower daily for at least the first 7 days.
Separate Laundry: Wash his clothes, towels, and bed linens separately from yours, especially during the first 3 days.
Stay Hydrated: Encourage him to drink plenty of fluids to flush the radioactive material out of his system more quickly.
Distance: Maintain at least 3 feet of distance when possible for the first 3 days.
Sleep: Sleep in separate beds for at least 3 to 4 days.

Memorial Sloan Kettering Cancer Center recommendations

After the 3-Day Period
Deep Clean: After the initial 3-day high-risk period, thoroughly clean the bathroom, including the toilet, sink, and floor.
Disposal: The trash containing cleaning materials, wipes, and disposable items can generally be disposed of normally after this period, but some centers recommend holding it for a week or more.
Dartmouth's Geisel School of Medicine recommendations

Thankyou! That's so great to have all that information.
Unfortunately, because of the prostate cancer and then he just had a tumor removed at his spinal cord at T4, since November, he has mobility issues and can't just get up and walk to the bathroom and urinate, and he can't sit to urinate because of the TURP that he had done...So, he uses urinals...that gets really messy..I usually wear gloves, empty into the toilet and then wash them out...but with pluvicto that sounds pretty risky...I'm hoping they'll keep him in the hospital for a few days..I'm in Canada, and they actually said only 24 hours...but I would stay away at least 2 days, and now with the info you sent, I would stay away for a week..

My husband had Pluvicto infusions at Mayo Rochester. Their radiation safety instructions were much less strict. They said we could ride in the car together and sleep in the same room right away without worrying. They did advise using separate toilets for a few days and said children and pregnant women should stay six feet away. The infusions are six weeks apart and the radiation declines pretty quickly after each one. No need to isolate the patient and no need to buy a Geiger counter as some men on this forum advocate.

Depending on the results of his next PSMA PET scan, my husband will be turning to Pluvicto as his next treatment option. I have been monitoring this subject line for helpful hints to deal with it. I have read 2 people with first hand knowledge - both of them had gotten Geiger counters "to be sure" (I believe one had said that he had found it on-line for < $100). They would stay in separate bedrooms until their readings dropped enough - one of them said that it would take him a week to get to a reading of zero. I plan on going with a Geiger counter.
We also will have to find a way to keep the cats away from him.

I just dug out the instructions we received at Mayo Rochester from the team that gave my husband Pluvicto. Here they are:

For three days: drink at least eight glasses or water or other non-alcoholic liquid each day.
For one day: use separate bathrooms when possible.
Males should sit while using the toilet to prevent splashing of urine.
Clean up spilled urine yourself. Wipe with damp toilet tissue and flush down the toilet.
Flush twice, and close lid if applicable.
Contact with children under 10: For one day, Do not be closer than arms' length for an extended period of time.
Contact with pregnant women: For two days, sleep in separate bed from your partner if they are pregnant.
It is safe to share a bed with a person who is not pregnant or under 10 years old
You may travel home by car or plane immediately after treatment.
You may stay in a hotel the night of treatment.