I assume its the association with 'commercial' and 'weights' due to the fact that most are over 80" where you see ID lights. However the Federal and state codes specifically dealing with ID lighting requirements are addressing 'widths' and nothing to do with commercial or weight capacities and apply to all vehicles 80"+. Ie boat trailers, DRW pickup trucks, campers etc.
AS to the OPs question only pro I can see if the truck otherwise didn't require ID lights is they would not need to also be on camper (though may still need clearance lights). Does give more visibility but couldn't say any safer.
Cons, reflections off the nose, and loss of clearance if space an issue. Drilling holes in a perfectly good roof.
