Originally Posted by OldCoot
If the trailer has springs, jacking under the axle where the spring is clamped to the axle will do no harm whatsoever. Never jack or put jack stands on a torsion axle.
What it will do however is give the trailer some spring bounce while it is on the jack. That is not a good thing. So unless you have more information, I'll stick with the manufacturer's recommendation.
Let me also add that since all FR A-Frame campers have torsion axles, suggesting jacking under the axle at all is misinformation, because it does not apply to the OPs camper and could confuse a new and unknowledgeable owner into doing something that is dangerous and potentially damaging.