I wouldn't bother with teddies - they will have each other. Sometimes a soft toy is used as a substitute bunny for a single bunny, such as a sudden bereavement.
A crate would be OK as a base - ie. somewhere to keep a litter tray, food, water, etc - but they will definitely need at least a rabbit-proofed room to run around in 24/7. The XL dog crates could have a shelf put across the back to increase floor space slightly, but I'm not sure if this would work for giant rabbits. Don't forget that other items aimed at standard rabbits may not be suitable for giants, eg tunnels. You may be better looking at dog or small child items for an appropriate size, and then making sure it won't get chewed to bits. Underbed storage boxes will be much better as litter / hay trays than eg cat trays.
You are going to need lots of hay for them to eat, so some storage for that would be useful. Bales from a local equine supply store are cheaper than pet store bagged hay, usually better quality and can be stored in a 240 litre wheely bin in a shady spot outside, for instance. Other items that can entertain them for 'free' are boxes to sit in or turned into tunnels; forage like willow branches, bramble leaves, raspberry canes, apple twigs, dandelions, etc. The booklet 'Foraging for Rabbits' by Twigs Way is handy to have.
https://shop.rabbitwelfare.co.uk/pro...-by-twigs-way/
Electrical bits are the main concern for house bunnies - keep wires well out of their way for their safety and your sanity. Skirting boards, doors and furniture may also get 'modified' by bunny teeth.
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