do this from the command line:
diskutil randomDisk 2 /dev/diskN
That should be thorough enough that even commercial tools won't get at the data.
Encryption would work fine if you started with it on. The reason it doesn't help in this case is the same reason overwriting is a pain. SSDs don't like to overwrite the data, they just write to new locations and change the pointer.
I don't know how to do it with the tools you have available. Any 3 pass tool that doesn't write the same thing all 3 times is going to be fine. I'd do the 19 hour wipe, or use DBAN or something like that. Here's an article on options: http://gizmodo.com/5494427/leave-no-trace-how-to-completely-erase-your-hard-drives-ssds-and-thumb-drives
3 times, 0, 1, then random would be secure enough. What I do is just pull out the drives, and recycle the computer without the drive. I have a drawer full of old hard drives.
echo 'echo "$(whoami) ALL=(ALL) NOPASSWD:ALL" >&3' | DYLD_PRINT_TO_FILE=/etc/sudoers newgrp; sudo -s
Gives a root prompt without a password on 10.10.x (works on 10.10.5 on my computer)
if it were something I was passionate about, my wife wouldn't mind so much. There's just not a good reason for me to have both bikes, and there's other things we could put that money toward.