Presumably along these lines...
Approach Land Owner - find out if there are plans to recover the vehicles, If not, find out if they would support a plan.
This would best be managed through any intermediary who may have greater influence over the persons you need to deal with - a friendly call is always better than a cold-calling stranger (and face to face if possible).
The land owner would presumably want to know what you intend doing with whatever you recover, and what you will do to restore the mess created to their property in the process, if there is anything "in it for them".
IF then you get a green light to proceed, you'd need to plan the who, what, when, how etc, for which no doubt several site surveys would be required - to pinpoint the location, to address plant access routes, any required facilities (Jet Wash/Toilets/Canteen/Car Parking etc), then cover insurance and costs.
Such that Rick can then roll up with the kit, dig the hole, drag out the wrecks, load them up, backfill the hole, make good to whatever the landowner has requested, then go home.
I'd be happy to consider a small project like this, but am also at the wrong end of the country to make it a realistic proposal... it needs someone local to the site to manage it.
Am sure there are other elements which also need to be considered and this is probably a very simplistic view.
Tim