They are easy, and you can do it. But, and don't interpret me as trying to talk you out of buying one, you can achieve your goals without it.
I encourage them when: stock components are not being used (handlebar controls, lighting, etc), the stock harness is bothered beyond recognition, and relocation of electrical components is desirable. If you meet 2 of the 3 criteria, then absolutely, it makes everything much easier.
As for "naked" components on your bike, you can remove the horn and not effect the harness. You can remove lights, and not effect the harness. You can disconnect the wiring for the starter motor, and not effect the harness. So if your budget gets tight, then I'd question: "With a bare essentials bike, why Spend $300 on a multi-circuit digital fuse box to control functions you aren't going to be using?" See my point?
The M-unit controls all the lighting, the electric starter, the horn, etc. But you're ditching these things. From the sound of it, you really only need 2 fuses: MAIN and TAIL. Are you planning on running the stock ignition or switching to electronic?
You can wire your bike based upon the following diagram with as much ease as the M-unit provides, especially given how simplified a machine you plan to operate.
Maybe this makes better sense now-
