The idea above on using non-standard hardware is a great one. I'll be sure to protect my future PV Panels, etc., via that method.
A pal has had his CT full of Electrical contractor gear broken into and emptied twice around suburban Boulder CO, and the foothills. ~$20k of equipment lost each time. Thieves used a 'hardened' circular blade on a battery-powered Drill. RV Man56's super Album pix of his CT in 'our' CO mountains highlights how vulnerable a potential target a CT is while guessing at the valuable items inside.
All I've been able to think of for my future CT conversion is to install a Car-type security system that runs off the primary, enclosed battery in a vented battery box. The weatherpproofed siren could point down through holes in the [dropped?] floor. A mercury level switch from an old house thermostat could mount on a small arc of plywood near the door held by a wingnut. I would adjust the switch level [concealed in a Kitchen cab?] to be barely 'off' just before leaving. This would adjust for Trailer level at set up. If someone jacked the CT for towing w/chains sans a locked coupler ball, this level switch would close and set off the screaming alarm w/timer. Magnetic 'reed' switches would cover the other openings.
I think, with tweaking, this system would be relatively fool- and pet-proof. The only protection this system would provide would be via the surprise of the Alarm, and the difficulty of finding and disabling it. Pros and cons, I know... The 'stealth' factor advantage is why I don't post signs like 'This Property Is Protected By Smith & Wesson' on our remote House & Properties. Why warn thieving turdballs that I have loaded Concealed Carry weapons on site?
Removing a Tire sounds better than using a massive chain and lock through spoked Hubs. Chains can be cut, as can cam locks. What a hassle, though...
Toilet Flange info is likely in a Manual here:
http://www.thetford.com/Thetford/HOME/P ... fault.aspx
http://www.thetford.com/HOME/Applicatio ... fault.aspx