Advice on shelving and/or rat problems

Hi guys.
So you guys know a while back I had that kit with it's foreleg bitten off. He's all grown now and actually was rehired in the end and has a great new family. He hops and binkies with no issues. I had thought his mom had bitten it, a few of you said it could have been a rat. I didn't believe it since my cages are 4 feet off the ground on poles, but now I'm not so sure.
Another of my does had a litter, she's always the sweetest momma, loves cuddling her kits. Went out one day to find one of the 3 week old kits dead in the nest box(I had left the box in cause her kits always love cuddling in it), with it's foreleg bitten off just like the last one. I was shocked because it was a different doe, different age kit. The only connection was it was the same cage. Maybe it was a rat after all? Can rats bite off legs of 3 week old kits? Anyways I brought her kits inside at night after that, brought them back out during the day, and had no more issues with the litter.

Point is, my Rex is expecting her first litter next week. I'm nervous to leave her kits in case a rat kills them. What can I do about the problem if it was a rat? I can't find any trace of them otherwise. I think they're coming from the neighbors yard maybe.
I'm thinking of just shelving the kits at night and continuing to bring them in until they're quite big. What is a safe age to leave them outside?
Also, with shelving newborns, does it matter what time they're with the mom? Will she only nurse them at a certain time?

I'm guessing that it doesn't matter what time nursing takes place as long as it's 24 hours between feedings so she has time to produce milk.

I find that sunrise and sunset are the best times to feed shelved kits, with the moms being much more apt to feed in the morning, than in the evening.

Yes, a rat could definitely be your culprit, and thankfully shelving is a good solution, as its really hard to get rid of the buggers.

Depending upon the size of the rat, and what it wants, I'm not sure any rabbit is truly ever safe. Just by being in the same area they can be spreading disease, and as far as physical attacks, I have no problem imagining them attacking an adult, in the right situation. They are foragers and they are on the hunt for food, and just about anything will do if other sources become unavailable.

Rat traps, poison, and cones, like they make to deter squirrels on bird feeders may help too.

If rats get bold enough they'll attack just about anything and be a challenge even for a small adult rabbit. Usually it's not worth that and they won't go after things that actually fight back but being herbivores that would rely on running rather than fighting rabbits don't really get their territorial instincts until they are mature enough to breed.

You rarely see rats until the population gets rather impressive. If they are wandering from another property you may never see them. While consistently putting out plaster bait (mix modeling plaster with any edible food item such as peanut butter or roll in tasty food items and replace as it dries too hard) will eventually kill them I always end up turning to commercial rat poison to thoroughly be rid of them. I've tried every trap commercial and homemade with minimal luck, all sorts of baits, and a bunch of things like plaster that are not toxic to other animals but they persist until I just leave a small amount of poison out. I decided it's better to kill them off quickly with carefully protected poison bait in locking bait stations than to mess around with other options, let them multiply, lose some animals, and end up poisoning a much larger number eventually.