Be responsible for your actions and leave no garbage behind to maintain a welcome status. At this point you will need to build radio gear and antennas that you can transport in your vehicle. This site has designs for both. Feel free to build, modify or design your own. There is a really good shielded loop in the Library of the Longwave pages .
Vertical antennas are the easiest and most economical to build.
Check out the roof top and door mount tubing vertical s and holders. The downside with these vehicle mounted antennas is microphonics. You will need to be quiet in your vehicle during recording sessions as any antenna like this will also act as a microphone. A much better approach is to construct a small portable mast with 3 guys and anchors. A portable loop can be built which plugs into the mast and a second holder for a vertical hi-Z field probe can also be included.