I raise the wheels off the ground and place a pair of automotive jack stands on the frame just behind the axle
. They are inexpensive and available at Walmart or auto parts stores. (Avoid Harbor Freight- they had several recent recalls on their jack stands.) Then I deploy the rear stabilizers, so it rests on 5 points: jack stands, stabilizers, and tongue jack. Very solid and allows the rubber in the axle
to relax while stored. If needed, put concrete pavers under the stands to keep them from sinking in soft ground.
If possible, park it on concrete, asphalt, or gravel rather than grass or dirt, which can accelerate rust in the undercarriage. Avoid areas where rodents are active and/or put out bait stations near the trailer. Make sure there’s good drainage, no standing water. Protect the tires
from sun exposure.
If you store outside in the snow belt and will not be able to remove accumulating snow regularly, you might add a floor to ceiling brace inside the trailer. A 2z6 between squares of 3/4” plywood will do the job.
If humidity is a problem, put chemical desiccants in the trailer (Dri-Rid?) and check regularly. Remove and store cushions indoors. Remove food and paper goods, anything that might attract critters or encourage nesting. Leave cabinet doors and fridge
open to circulate air.