I built an NTSC ISO that retains the normal retail game filesystem. (as in uses Apploader with working opening.bnr file among others)
It boots on my XenoGC modchipped GameCube:
SwissGCMISO.rar
I've burnt this to my own DVD and shows up in GameCube BIOS with correct banner and description. It boots and I have had no issues with it. I'm not sure if anyone has built a Swiss ISO in this manner, so pull the link if it's redundant or not allowed.
This ISO uses Swiss v0.3 r241.
I recall using the WiiFusion version of Swiss and simply replaced the Apploader.ldr file with Swiss and it boots. Of coarse all files relating to Mario Kart that the GCM file originally had were removed. It's untrimmed as well by the way (only 900 or so KB due to RAR file compression). Rebuilt using GCRebuilder.
When I boot this it automatically searches for a SD card on the memory card slots then displays the current DVD loaded in the GameCube. Should work on a softmodded/chipped Wii as well.