I have no experience with the windows you describe but...
It is highly Unlikely they are soldered. Solder is an alloy of lead, antimony, and sometimes silver. Except for something exotic, I don't believe those alloys adhere to aluminum.
Chances are the corners that appear to be "soldered" are actually welded. SOME Aluminum alloys may be TIG or MIG welded. (2024 doesn't weld but other series do and if other windows on the AS are welded surely the one you're working on is the same alloy....)
Another solution might be to use blind rivets. Why isn't that a solution for you?
2012 Ram 1500 Crew Cab Tradesman 4.7L 4X4