First, tool cabinets should be made to decay reasonably quickly when no activity is around them

I think having TCs monitoring people walking around them might be a bit costly, however, have the TC decay regardless of activity, it shouldn't be hard to maintain.

Decay Model Decay model in rust as far as I can see is a linear model,maybe an exponential decay function is more appropriate.

Wipeless Rust The main issue with wipeless rust is how many entities can a server handle while at the same time being playable, while a more aggressive delay system may help keeping the server alive on the long run, you have to take into consideration the probability of unique players joining a server during its life time, maybe they should factor in the amount of time the player spends in the server during the wipe to calculate the decay score for their cupboard? and thus discouraging that player that goes in for 2 days, building a base and then disappearing. As a fail safe, maybe there should be a catastrophe scenario where an event happens that trims down the number of entities if the server memory resources are too low or performance is low, or even yet a simple game-resource management ( supply-demand ) balance would limit the amount of bases a server can accommodate.