Got pipe insulation a couple weeks ago and blocked the upper grill. Not sure if it helps warm up much at 50-60F, but it seems to keep the warm up time similar to those temps even when it's 30 out. I think I'll need to do something about the gaping hole under the engine bay if I want to get any further temperature increases. I just need to get ramps or visit my parents again.
Discovered a bad thing about having the block heater plug come out the upper grill, it got completely covered in our first snow yesterday. Shouldn't be a shock hazard (I unplug the extension cord from the wall before leaving, so there's no power when I plug the heater in), but having it freeze together would not be fun.