I am sure you'll disagree with me on this one, as you and I have had some different thoughts so far.
My favorite anchorpoint on a vehicle is spokes on a wheel. All the lockout/tagout type procedures are used as discussed above. Of course, judgement is used per case, doing this with a Smartcar is not as advantageous as using a Ford F-350.
What we never use, any anchorpoint on the front or rear of the vehicle. There is too much play in the suspension that rocks back and fourth, that can lead to damaging equipment on edges. Anchoring on the wheels stays below the suspension, taking that play out of it.
Im out of an industrial setting and we have rienforced bumper mounts for our uni-hoist unit on the back of our two rescue vans (Ford Econoline Full Size). The unihoist also has its own extendable mount and we also have a tripod system.....but we have kind of moved away from using the vehicle mounts..... on occassion we'll still use it in a situation were we can back the van up, but the reality is when we do this our entire equipment moves with it right into the HOT zone of the space.....if we end up having a situation that is an atmosphere concern we could have issues with that....I think in the end taking the time to just set up the tri pod or the unihoist with its mount is much more effective for our particular situations...
In my department, we have engineered tow rings that are rated for the full weight of the vehicle - over 15 tons.
If you're not sure how the tow rings/hooks are anchored to the frame, a quick look will usually tell you whether the tow devices are substantial enough or not.
If the tow devices are not adequate or you are uncertain, just use the vehicle's axle as the anchor point - preferably the more substantial rear axle. An axle that is substantial enough to carry a multi-ton fire apparatus is substantial enough to support a rescue load.
All it takes to make this work is to extend the anchor from the axle to a point outside the vehicle's footprint to allow for easy manipulation of the hardware at the rigging collection point.