I understand your dilemma. I spent some time deciding if I wanted to take on that trailer when I had no idea how to lower it again.
We could afford to purchase a new Trillium but there is so much more character in the old ones that I tend to overlook the amount of work that is required to restore them - even with our clean 1976 I am looking at a gelcoat restore and fiberglass repair, rebuild or replacement of the rockscreen, new flooring and cabinet doors and some electrical
fixes and upgrades. Eventually the upholstery and cushions will need to be done, all in all a couple of thousand dollars and a lot of man hours.
The plus side is we will end up with OUR trailer, not a generic RV right out of the factory. I find the newer Trilliums (nice as they are) a bit impersonal and I just would not feel comfortable doing mods on a new $$$ trailer.
On a side note, Trillium Calgary has full frames/axles with electric brakes
for sale - more of a drive for you but it's another option and they look reasonably priced. If the frame bolts are in the same place it shouldn't be a huge deal to move the trailer over to the new frame.