You don't need portable apps to be able to store your apps on your SDHC card. The "portable" element for those is, I think, to do with preferences and other app-specific data which is normally stored in your Library folder in your home directory. I think this means that you can carry those things around with the app.
If all you are trying to do is save some space on your SSD
, then just put your applications on the SDHC card instead of in your Applications folder. Works with pretty much any application. The only ones I have difficulty with are some which insist on being installed on the boot volume (e.g. Xcode is taking up a load of my SSD
My setup is that I have a handful of my essential apps in my Application folder (Quicksilver, VNC and Slim Battery Monitor) so I can use them when I remove the SDHC card. Everything else is in an "Applications" partition on my SDHC card (e.g. Photoshop, VLC, SmartBackup, Skype, Adium, plus everything else). Not had any problems with this setup at all - and I've run a similar setup for years on every Mac that I've run OSX on (although using a HD partition rather than an SDHC one).
I started doing it to make it easier to manage things for backups, multiple machines, etc., but it was really useful on the Mini 9 to give me space for all my apps.
To install stuff on the Applications volume, I either just drag it from the DMG (or whatever) or if the app uses an installer, I select "change destination" and most installers will let you switch to a different volume to install.
So, I don't think you're restricted to these portable apps to stick on your SD card - you should be able to do it with pretty much any app.