I'm not super educated on MTP, but I think it is the "magic" that lets some phones talk to computers via USB. The magic part is that an MTP connection isn't like plugging in a new drive. It has it's own protocol and it's own limitations.
On the other hand, if you take your SD card, put it into a USB adapter, and plug that into your computer, the SD card should appear just like any other drive to your computer. You pretty much said that above; I just wanted to be explicit about it.
With that kind of setup, you should have all of MC's handheld options available to you.
Another way to do this is to do your handheld staging area, and then use a phone transfer tool to move the files from the staging area to the storage card in the phone. Windows may be able to natively transfer files to your phone. Or you might need Google's "Android File Transfer" program to do it. That what I use, but I'm on a Mac; not Windows.
I also routinely plug a micro-SD card into a reader and use MC to update the card directly, including playlists in M3U format.
Good luck.
Brian.