The problem with that is it becomes a regressive tax that impacts the price of all goods transported by truck and raises the prices of basic necessities.

I think the suggestion I saw that all road maintenance should be paid from the general fund makes the most sense.

This would subsidize truck and private car transport against rail, which is counterproductive if you are trying to lower the long term costs of transport and decrease transport externalities (e.g. fine particle pollution, noise, climate change).