You could overwinter your young Japanese maple in any one of your locations. If you place it in your heated sun room it will continue growing so you will need to water it. 

Thanks for quick reply.  Can you please tell me if among these options, there is a preferred method or preferred location?

Thanks for your note.

There are many types of Japanese maples. Some varieties will survive our cold winters and grow well when planted outside in a protected location. Then years later, it will be killed off by a late spring freeze when the tree is coming out of dormancy.  Other varieties of Japanese maple trees are only able to survive in zone 5.  Many people overwinter dormant container plants in their attached unheated garage.  Dormant trees do not require any light. The containers must receive enough water to keep the soil from drying out.The humidity is very low in the winter in a unheated garage so the dormant plants must be watered often.  The garage must stay between 30-40 F.  If the garage gets too warm the tree will come out of dormancy to early in the spring and require light. Maples have shallow roots so they will die if the soil dries out completely. A 10 inch container will dry out very quickly. I prefer to overwinter most of my young container trees in sunny windows at room temperature. They often continue to grow during the winter. The dormant trees that I grow in a cooler basement or garage often die because I forget to water them often enough. Grouping plants together or growing with a humidity try helps to increase the localized humidity.

My JM tree is an Acer, zone 5. Your explanation was v helpful.  Thank you!