Tow Pro: Wheel bearings

It seems from reading that wheel bearings failure is one of the most common caravan failures, so it is recommended that you feel the wheel hubs for overheating when ever you stop. That is not possible with most new vans as they have centre hub covers fitted stopping access to feeling the bearing hubs, so how can I carry out this check? Do you recommend self greasing wheel bearing hubs which I have seen in automotive shops I think mainly for boat trailers. Would this help cut down on bearing failures?

John Burges, WA