"I think I can use the resulting disfigurement and stressed look to
advantage in the overall garden bed design, but I can't tolerate total
death, the 4' specimen offered for sale is expensive."

I'm all for zone pushing and have always done so no matter where I have lived but only with the understanding that I might lose my investment the first season.

It's a gamble, and like any sort of gambling it would be wise to only spend what you can afford to lose.

Most folks living in USDA 4 do not grow any Acer palmatums - none are really hardiness rated to that zone and as they are generally not inexpensive trees, most will opt for something that will survive that climate without undo concern. There are cold hardy Asian or hybrid maples that will thrive in that climate but any Acer palmatum......not so much. I can't think of any regular posters to this forum who grow JM's in that climate but maybe someone will chime in.

If you want to experiment, you can create your own microclimate: site out of any direct wind (shielded by other plants - preferrably evergreen - a courtyard, building alcove or "L") and where it may benefit from any reflected heat from the house or other structure or from any paving. And mulch well.

The focus of this inquiry is on the two questions posted in the OP, thanks in advance!

I hope you have your patient pants on because for the various reasons listed by other posters above, I doubt you will get many locational specific responses to your question.

Japanese maples of ANY variety are just not reliably hardy below zone 5 and few gardeners in zone 4 attempt to grow them. Those that do, focus on the cast iron varieties, like the straight species or Emperor 1 or a very few other late to leaf out selections. And even those are no guarantee for a long term survival rate. Or they grow them in containers and move to a protected location for winter.

I can tell you this... a good gardening friend with hundreds of JMs has had a hard time getting Shishigashira to live through average 5b winters. In fact, none have. He's still trying, though! I get the appeal...it's a fascinating tree. So unless you plan on potting it and protecting it over the winter, I'd say zone 4 is too much.

Hundreds of JMs? Commercial operation?

Anyway, the few nurseries here that showcase (a few) JMs grow them in South-East facing L-shaped building corners, often with an overhead sunscreen. The tight shelters look more like unattractive greenhouse corners than attractive showcases, but the JMs apparently survive cold zone 4b winters, although I have not seen a Shishigashira specimen grown like that.

Not a commercial operation, just a very (!) avid collector. All planted in the ground, with forest/wind shelter in 5b.

Good luck! If it works for you, please post.

Ha ha I won't play the pioneer, I gladly leave that to others and let them tell their stories, see OP :-)

Grow it in a pot and drag it into the garage during the coldest months of the year. They grow slow to 12 feet. If you pruned tree and roots every few years you could keep it to about 6-7 feet.