Frankly, if you put a tilt head up there that's loose enough to pull by string, it will soon flop around and work itself lose. So many centrifugal forces, kinda like being on Dooley's tail.
Yes, if you don't put some friction into it, it would probably shake loose eventually. I don't think the lateral forces are as great as Dooley's tail. He gets to wagging that thing so fast that sometimes I wonder why it doesn't fly right off of his butt.
I was thinking more of some friction washers so that there was some resistance, and using a spring against a string to hold it in tilt position. The spring would normally keep the camera level. Pulling the string would load the spring, and tilt the camera down. The spring would maintain tension and keep it tight. There would have to be some spring tension still in the fully level position with some kind of movement stop. I have an idea of how to do that with just a short piece of the "Hobie standard" black bungee and a circle cut out of something like starboard. (I found a sheet of the stuff while beach combing) With this approach, you just need a string running down between the mast and sail sleeve. You pull the camera down to the tilt position you want, and then snug up the string. That makes the lower end simple, too.
Simplicity is way key here. I've got this down to one moving part.
On the Pentax, I used a pocket W80 for over a year and loved it. It wasn't quite as good in image quality as the Nikon AW100 that I carry now, but it has some great features and I wouldn't be adverse to another Pentax product. The W80 eventually died because it's made out of soft plastic. Pure and simple. Eventually, it leaks somewhere. Still, for the money, I got a hard year's use out of it and would certainly buy another one, if I didn't have the Nikon.
We also have a Kx1 Pentax which is an okay DSLR, except that it scarfs up Alkaline AA batteries 4 at a time ( SUCKS!) and is useless for video. We bought two of them, and at least one has always been broken. One's broken right now. Good stills, though, if you don't mind dealing with dust spots on the sensor a lot. I eventually got tired of cleaning it and just use Paintshop to erase the spots. Now that I think about it, I would not buy another one of those. Primarily for the battery hassle.
I've got lots of dessicants. I think I cleaned Amazon out last year when I was trying to fix this. I've been trying the extended battery case for the extra room, and sticking five dessicant packs in there, and it still fogs up.
Next step is to store and assemble it all in a low humidity environment. I have been thinking about that. How to fill it with dry air to start with. Perhaps drill a couple holes in the housing, and install some ports to flush with some kind of gas or dry air? Dedicate that housing to mast top.
lately, I've just been using the vented back for the cases, which works at the top of the mast but not on the swimming dog. Fogging is much less of a problem doing time lapse. It's the video where it really messes up.
Island life in the Devil's Triangle: http://2gringos.blogspot.com