Love all the work that you've done and it looks great - but just thought I'd give some feedback on the purchased options. I bought the super cheap ($120 at the time) 2 bike, hitch mounted rack from Cyclingdeal.com about 2.5 years ago.
http://www.cyclingdeal.com.au/buy/2-bicycle-bike-rack-hitch-mount-carrier-car/CB-640A
I was worried that it couldn't possible be any good at that price - and it doesn't look fancy. But it has been fantastic. All my mates look on jealously when I load my bikes in 30sec max. Can't say how much better it is to have the bikes sitting in steel loops rather than hanging off something - no damage to frames, hoops stop bike moving at all. Its never had a problem and it's finally stopped me trashing bikes and roof racks by driving them into my carport! I've loaded $6000 carbon road bikes, 29er MTBs, whatever - just seems to fit everything and I love that there are no straps or keys or locks - nothing. If I want it secure I wrap and cable around it. When I don't use it I fold it up and even that is quick and reliable. All just so simple.
The only issue I had was when purchased I had to saw off about 20mm from the 50x50 square tubing that goes into the hitch mount because it was too long. That took 15 minutes with an angle grinder and haven't looked back. And last thing, it arrived two days after ordering - can't even work out how that happened!
Re the light and number plate thing, I normally just cable tie on an old number plate holder I have. On longer trips I have used a light that hangs off it that I scrounged from an old bike holder. I know I'm prob meant to do this more often but have never had an issue and have driven it thousands of ks.