The front and rear scissor jacks are stabilizer jacks. While they may have the ability to support the entire weight of the TT, they are not intended to be used in that manner. For long term storage, I would not use the stabilizer jacks at all; simply let the wheels and tongue jack support the weight. My TT sits this way while stored in a limestone mine for six months during the winter. When my tires are in good condition, properly inflated and valves aren't leaking, I only lose about five pounds of air when I take it back out in the spring. Think about it. Trailers sit this way on dealer lots for sometimes a year or more with no issues.
2009 GMC Sierra 2500HD | Crew Cab | Standard Box | 4WD | Duramax/Allison
2000 Jayco Eagle 266 | FBS | TT
1986 Coleman Laramie pop-up -- Still in the family!!!