I'd agree with Jimm... just block the trem. It won't quite give you the same low-end
“oomph” that you'll get from a fixed bridge (especially with the strings through the body), but it'll be easier and more versatile should you change your mind later.
Also, if you want to experiment with dropped tunings, you want a
longer scale length, not a shorter one. The longer scale length (along with heavier strings) will give you added
string tension which will help compensate for the “floppiness” you get when you drop the tuning.
Warmoth makes baritone retrofit necks that fit 25.5´´ scale length guitars like your Radius. They have 27´´
scale lengths.