I remember that, Brock. I'm sorry that happened to you, but now you can say from experience that Caps need lower temps. Even with most of the greatest SH minds in the world helping, poor Brock couldn't save his little Cap.
The public aquariums that we know of keeping caps keep them way below 68* even. Low 60's is ideal.
Tbar, if you can keep your tank at 69-70, you could keep whitei, which is a "subtropical" SH. if you can get it lower than 69, you could keep breviceps.
Don't let us scare you, though. If you do decide to get those caps, please keep us updated no matter what the outcome is. It's important in the world of syngnathids to report our successes and failures.