What does MTL use for the axles between their loco wheels? It melts after 30 seconds stalls shorted at the points of a DCC powered track.
Probably Delrin or some engineering plastic. But loco wheels usually have very large shoulders to strengthen the axle; often these shoulders run right up to the gear. That's for the GP-35 design, anyway, which is based on their 70s era F units. Newer ones I have no idea, but usually the wheels are turned with a solid axle that fits in plastic sleeves molded onto the sides of the gear, so there's a lot of extra material there to make it rigid.
I'm not saying it wouldn't work, I'm just suggesting it should take some more thought to avoid known pitfalls, like those bad old Kadee N scale wheelsets. And what's it going to look like? If the axle is hugely thick, or the wheels are shapen oddly to compensate for the lack of strength in the insulating material, it might not be worth it from an aesthetic standpoint, at least to me.