I can't think of any particular problems. 24V wiring is in the same sort of regulatory class as 12V wiring if my memory serves me. ATC fuses and many automotive wiring connectors or contacts and similar items are frequently rated for 24V (or higher), so finding such parts should not be a big difficulty.
At least for lights, and probably for many other devices, you should be able to find 24V equivalents which would reduce the size required for the (rather substantial) DC-DC converter. One advantage of using 24V for as many of the loads as practical is that you reduce the power loss due to voltage drop by a factor of four, all other things being equal.