Reddit reviews GNB PET Natural Wood Stand Platform 5‘’x11'' for Hamster Mice Chinchilla Chipmunk, Small Animals Habitat Toy HM-10

Best thing I could find (10.7 x 18.4 x 8)

The only thing I would worry about is the little ones chewing on the coating, this size should cover 1/3 long ways.

Also you may be able to use the hooks on this not only as a stand but you could make very small holes and hook it to add even more room.

However if this doesn't work, you could add adhesive hooks so you can use cage hooking items like this

If the hooks aren't what you want then you can add items like these:

Best Option

Wooden Balcony

Platform

Platform and Swing

Platform and Swing - The Squeequel

I really hope this will help you and the little ones out!

Edit: Forgot to add this one

5x11 platform

3 pack mini platforms

Peek a Boo tunnel (she has a shop on Etsy as well)

Hanging bridge

Niteangel wooden house (unfortunately out of stock)

Etsy has a lot of chinchilla ledges, bridges and other cage accessories, definitely check them out. Shipping can be really slow though but the quality is worth it.

We also have a penny candy jar we're trying to train him to get into for transport since he hates being picked up but he mostly just likes perching on top of it at the moment.