Snow sliding off a metal roof can weigh hundreds of pound and is somewhat compacted to start with. People have been killed by ice/snow sliding off a roof. Burlap wouldn't be of much help other than from wind burning.

If you have a problem with snow, you can install ice guards on the lower part that prevent sliding from happening. Then of course, you can have build up during bad years and the snow will have to be removed.

One idea would be to get some 2x4's and a screw gun. Build a framed structure over the tree to protect it until it gets some size. Just 4' apart at the corners, some braces and a few 2x4's spaced an inch or so apart, over the top would keep the icy avalanche from crushing the tree. Whatever you build, it's going to have to be sturdy.

That or plant the tree further out from under the eves of the house.

Maybe you could inquire over in the building forums for ideas. They may have some better/easier ideas.

It's not a metal roof. I may be worrying too much, because our winter two years ago was on the high end of snow and ice, with no intermediate melts.

The only time I've seen snow/ice problems on roofs that were not metal, was when rain gutters filled with snow & ice and after a time became so heavy that the weight pulled the gutters off the facia and the whole thing fell with a crash. Otherwise if you don't have gutters, snow overhang from drifting on the edge of the roof can eventually break off and fall in one chunk but that's uncommon and if you keep an eye on things, you can take a roof rake and remove any build up before it gets serious. Another method is to install roof heat cable along the bottom foot or so of the shingles. This takes electricity but will keep snow/ice from building up along the roof edge and you won't have to go out in the cold.

I would move the maple. It's only been in place just over two years.

Less than that as the OP replaced the damaged original last spring.

Even easier! :-)

Clearly this is not a place for a Japanese maple.

I put in a alpine rock garden for my brother with a metal roof in northern Idaho. He had snow five feet deep on the roof slide off on to the garden and no damage was discovered the following Spring. The snow piled up so far he couldn't see out the windows or sliding glass door.

I would hope that the OP's situation isn't quite as bad as the mountains of Idaho. :-) but yeah, JM's are pretty delicate. Now if he has a small cove built into the construction of the house or is just set on having this particular location, the best remedy for what he specified (as a shingled roof) would be to have a length or two of heat cable installed along the edge of the roof above the tree. Plug it in only when getting new snow or blowing snow and maybe leave it plugged when winter is at it's worst. Most years, in what the OP specified as area 6a, shouldn't be all that bad.