Mounting the wingtips is very straightforward. Just follow the instructions. Definitely use a foam insert to hold the structure rigid when drilling the holes. I did use platenuts. I hear of folks pop riveting the tips in place and I can't imaging why. I will need to get in there one day.
I choose to use the recessed lighting option from Vans. It works very well but I would suggest the following sequence instead of the recommended version.
1. fit the lens to the mount first. Including platenuts.
2. Once the lens fits the mount perfectly, use the lens as a template on the wingtip for cutting out the hole. This is an excellent starting point and makes life much simpler than trying to follow all those measurements the instructions try and give you.
3. Sand, fill, cut the mount into the tip. Patience is your friend here. Remember, taking off is easier than putting back.
4. Mount the light into the tip. CAUTION!! Do not center the light into the mount. It will hit the lens. You will have to shift the strobe portion up to clear the lens. See picture.
5. Be prepared to sand the fore and aft edges of the tip to get a smooth transition from tip to lens. Also be ready with some filler. I really like the looks of this compared to mounting it externally like by buddy Paul did.