I’m still not confident enough to try a ‘traditional’ fender style truss rod (front or back fitted). However the type I used for the last build requires taking the neck off to adjust it, which is fairly annoying. My Peavey 7-String has a spoke nut truss rod which worked really well, as does my Music man. This type has a wheel which sticks out the bottom of the neck which you can get to between the strings. The only place I could find them to buy was from America but they aren’t too bad to import.
I used the side rail on my router for the first time, along with a bit that can plunge route, which gave a really nice channel.
I had to couter drill a large channel for the spoke nut, which was a bit of a challenge as my cheap 10mm drill bit didn’t like the hard maple. I’ll have to source a nicer one for next time (my nice drill bit set only goes upto 8mm).