I will take a pix of the deadbolt tomorrow and post but here are the details.
Basically it is installed just as in any door. You drill a 2 1/8" hole through the door with a hole saw, (actually drill in from both sides for a cleaner cut). And drill a 1" hole in the door edge. These sizes and a template are included with the deadbolt, just like they are includes with a new doorknob. So you don't have to remember them.
The tricky part is getting the big hole in the correct place as the template cannot be used in its customary position, wrapped around the door, because of the lip on the outside of the door. To get around this I folded the template and used it only on the back side to get the correct backset distance (distance that the center of the bolt is from the edge of the door). I then drilled a pilot hole from that side thru to the other side, then use the hole saw to make the cut in from each side. You always want to drill IN on a finished surface whenever possible.
The bolt aligned nicely with the back edge of the lip on the door jamb, so the latch plate was not used, only a thin plastic spacer glued to the back of the jamb lip. So you must be careful when drilling the bolt hole in the door edge so that the bolt does not want to come out centered on the jamb lip. It must be behind it. But you have some allowance for this as the thickness of your door seal material will effect the placement of the door.
We found the Kwikset deadbolt online (cannot remember where) only because we wanted polished chrome to match the hinges, and this model has an option for thick doors which is a must. The Burro
door is 2 1/4" thick. Most doors are 1 3/4" thick. The extension thing just makes the mounting screws and bolt moving pin longer. Total for bolt and extension was under $20.
If you are filling smallish holes in interior or exterior of the Burro, there is a great epoxy product in a clear plastic tube, shaped like a Tootsie Roll. It's called "Water Patch" or something like that. It contains 2 part epoxy which is thick like plumbers putty. You slice off the appropriate amount then kneed it like pastry dough to mix the 2 parts together till the color is fairly even you won't get it perfectly mixed but that's not needed). Then just jamb it into the holes enough so that some product protrudes through the hole to help hold it in place. Use a smooth sharp plastic blade like an old credit card to scrape it smooth. It is kinda dry and sticky so you will learn on the first few holes. Spend time to get this as smooth as you can since is will be VERY hard when cured the next day. It is difficult but not impossible to sand. It WILL be impossible to sand it without scratching the surrounding FG surface, so apply it with care.
This stuff is very strong and the best part is that it is almost the same off white as the Burro Gelcoat (a little bit darker). It is very sticky so wear latex gloves when kneading it.