The switches may be marked for rating, but a relay will sort it and prevent fires. Although a fire in the right place will help visibility.
As these lights will not be 'E' marked for vehicle external use, take care when using them. If they dazzle, someone might complain.
It is still possible to get proper 'E' marked reversing lights. I used to fit one at the nearside, under the bumper, so never shining at anyone, to light the kerb, for when teaching the left reverse when dark. Feed from the car reverse light to trigger a relay, via a switch, for choice when to use. Later one did get more complicated, as I wired it so that it would only work if the sidelamps were lit, and reverse selected.
Rear fog lights can help when reversing. Hazards tend to distract more than help.
I'd suggest, a relay, how many depends on rating and whether you want choices of how many lights to use at any time, fed via your switches, but also connected to the van reverse circuit, so they can only be used when reverse gear is selected. Prevents leaving them on.
Good luck with them, its cold outside working on vehicles.