The Lemans are technically malibus, 😉 So I usually mention it in my posts. I asked on my FB LeMans owners group & apparently. where it plugs into its way far back on the DRs side firewall between the brake master cylinder & the fuse block. As I was told, there should be an open spot for it, because it is wired into the battery/light harness. Supposedly.Hmm. Not familiar with LeMans stuff, but I was under the impression that the underhood light harness was included in the forward lamp harness already regardless if equipped with underhood lamp or not. I could be wrong, but many cars without TR9 in the Cutlass realm I've ran across had the plug taped up in the forward harness. Just run the lamp and its wire and find the plugs and boom, instant underhood light. Too bad yours doesn't already have that.
As far as running the trunk lamp, yes, right down the inside of trunk lid and then along the hinge. On the Cutlass there are plastic wire clips that insert into punched holes on the hinge to hold the wiring in place. Then you can run it any way you want in the cabin, but normally it would be in the wire bundle under the left edge of the carpet up to the fuse block.
Yes!, the routing of that trunk lamp sounds about right. I'll have to check that hinge though, to see if it did have any Wire Loom Routing Clips. Not sure about the exact ID on them. Slightly off-topic but relatable. I was told for the Rear speaker harness (which I finally found & bought an uncut original one) thankfully. They had a few wire loom clips spaced out every few inches on the backside of the trunk wall where that harness would have been placed.
I need to look into that, but my trunk is Plumb full right now, on Wednesday i pulled out my seats & carpet to check the floor pans to see if they need any cleaning up. going to coat that floor next. Best bang for budget coater out there you could suggest? or even a surface Rust converter?