3 routers, 3 subnets with shortest path

I was trying to decide if this fit more in the home networking section, but the point of my experiment is to have a model of a more complex enterprise environment.

Here's a simple diagram: https://imgur.com/a/4vzL8JE

What I'm trying to set up is network that consists of 3 routers on 3 different subnets. I've picked up 3 WRT54GL v1.1 routers to try and do this on a budget. I have no problems getting devices on the 192.168.2.0 network to talk to the 192.168.3.0 devices via the 192.168.1.0 router. However, I can't figure out how to create the direct route between the 2 without going through 192.168.1.0. I was also hoping to find a way to make it resilient to a cable being disconnected, but maybe that's asking way too much from this consumer grade hardware?

Is this a limitation of using consumer level WRT54GL hardware? I was able to achieve the existing configuration by connecting the WAN ports on the 2 lower routers to the LAN ports on the upper one, and adding the routes to the routing table on 192.168.1.0. For that to work, routers 2 and 3 are both addressable on the 1 network. However, when connecting between the 2 LAN ports, I don't see a way to assign them the 2 IP addresses necessary for them to communicate directly.

If this isn't possible, what hardware should I be using? I feel like it's a simple scenario. I do have a few Cisco 3550s available if they would be better to use, but I'm not familiar with configuring them.

Sorry if this was too simple. I'm mostly trying to figure out if I need to go back to the drawing board or if it would be possible to use the 3550s to not have to buy new hardware.

Thank you!