That sure does sound like disaster in the making. NO WAY would I work around a RV with one end jacked up 14-inches with some homemade jack system...
Surely you can extend a portion of your driveway to the side of the garage where it gets level and park your RV in that area if your home area would allow something like that.. Something like this would be great...

Some folks I know will rent out a space in a nearby farm barn to park the hugh RV in...
Please be safe in whatever you come up with.
We have had a family member get crushed to death working under his jacked up truck...
Roy Ken