Hmmm, would be interesting to see if that works.
Not sure if HOTSPOT mode supports a single mode on the host router side and something different on the client side. It's possible it should work.
One thing you could do for the older LT, upgrade the WiFi on it. Get a newer WiFi adapter card installed, if it doesn't have that option to upgrade, get a DWA USB adapter card. If it's not used much, then the USB option would be a good solution to get it able to use WPA2 and AES.