I did some more research, and it looks like my original idea would require some modification to an existing repeater in order to work.
If my simplex node opens its squelch on the repeater transmit (with ctcss or otherwise), then hangtime and courtesy tones will make it in to the internet link. The people running the network don't want this.
The only way to truly make this work would be to find a repeater that passes ctcss tones through itself - i.e. it doesn't have a tone, but would re-transmit any tone it receives. I went looking around and didn't find any in calgary that did this, which makes me suspect that most repeaters filter out and re-synthesize PL tones rather than passing them through.
Any ideas on how I could increase the range of my node would be appreciated. I considered moving it up higher, but I don't know if (as a group) we have access to such a location.
Thanks!