In a nutshell, I think that's the right way to do it. Not trying to be a smart guy about this, but I really think some folks stay away from tanto blades because they don't know how to sharpen them. It's actually pretty easy, and once you get your system down it doesn't take very long at all.
I personally sharpen the main edge on a 1200 grit oval rod, the same way I sharpen all my other knives. I can touch up the second Edge at the tip easily if I am very careful with the same rod. If the point edge requires more work then I pull out a whetstone and freehand it. After I set the bevels on any knife I own to the proper degree that satisfies me, I never use a guided system anyway. I grew up freehanding, and have spent a lot of time learning how to do it properly. Once mastered, you can sharpen just about anything if you think it through before you start.
I used the second edge at the tip out on the job site as a chisel when it is sharp and more of a scraper, when it isn't. Sometimes (*ouch*) as a mini prying tool. Because that edge is so small on any of my three tantos, even if I goof up the point edge pretty badly I can quickly repair it. Love my tantos as job site knives for their tremendous utility value.
Robert