+1 on what John said. If you went with some 180-degree light on the sides of the dump body, that would certainly cover your side warning, but I would still recommend forward & rear facing lights to serve as your primary front/rear warning
I love Whelen, but their rotabeams and V-series surface Mount lights are a overpriced IMO. In this case, I would recommend looking into SoundOff surface Mount intersectors for the sides (they provide approx 180 degree coverage) and I would have forward and rear facing surface Mount soundoff Mpower fascia 4” lightheads. The mpowers are super rugged b/c of their silicone construction (which I think makes them a winner for a dump truck), they’re low profile, and they can be ordered in dual color (amber flashing with steady-burn white for some area/work lighting). You could also scrap the 180-degree intersectors all together and just put some mpowers on the side of the dump too
Good points and I agree with you.
The V series and rota-beams are a product I like, but the applications are limited and the price is high. Sound Off is always my second choice "or on a budget" choice. There are lots of options, but sticking to a basic "DOT" setup is probably more effective and cost friendly. There isn't anything I would recommended for 180 degree coverage that is worth the money for what you are doing IMHO. It's too bad Whelen has discontinued their "headboard" LEDs, those were a nice mounting option to get 180+ degrees from a surface mount/sealed light. They are trying to fill that market with the V versions of lightheads and the rota-beam 600, but it's not quite the same coverage. Out of all the V style lightheads I do like the M6 and M9 V versions the most as they give you a downward flood and a bigger 180 degree surface than the other options. But again the price is probably not worth it for the application.
The surface mount intersector from Sound Off is a good cost saving alternative like pdk9 said, but I also agree that the 180 degree portion of the build could be eliminated and covered by other means if cost is a factor. However if you plan to speak to the issue of 180 degree light with a beacon, the market is also not great. I don't think any of the 360 degree beacons really come close to Whelen's L31 and L32, but those models are priced at the cost of a mini bar. You could buy a LED responder or Century mini bar for each side for less than a pair of quality 360 degree beacons. If you plan to speak to the side/180 degree issue with more surface mount lightheads, the "hundred series" super LEDs from Whelen have dropped in price dramatically and there are lots of different cast and HD mounts for them. You could make your own "headboard" out of surface mount LEDs of your choice. You could do the same thing with Sound Off.
I recommend going over to
Strobes n' More . com and comparing the lightheads, beacons and minibars. They stock everything we are discussing and they have low prices. Compare everything with and without the 600 rota-beam, intersector, beacons, mini bars etc and see what the most bang for your buck is and what suits your taste in mounting.