Personal letter

I’m privately printing my maternal grandfather’s diary written in a Field Message Book during the first two years of WWI. Among other things, I’m including scans of items in my, or a relative’s, possession. In the Reference List at the end of the book, I’m really stumped how to word the first part of a citation for a letter from my grandfather, William Robert Bruce, to my grandmother, his wife, Ethel Sarah (Phelps) Bruce. I'll just be showing the first page where he mentions being gone, "a whole year; one long year of separation."

The heading of his letter is: 

     In the field.

     11.7.15

Salutation: My own Dear Wife.

Signed: Ever Your Will.

I’m new to using Evidence Explained, have worked diligently to find a solution myself, and have narrowed it down to one of the following—but which one? Or something else?

1. From EE, 3rd edition, 3.35:

Will [William Robert Bruce] (In the field) to "My own Dear Wife" [Ethel Sarah (Phelps) Bruce], letter, 11 July 1915;

2. But, I’d really like his given name as lead element:

[William Robert Bruce] Will (In the field) to "My own Dear Wife" [Ethel Sarah (Phelps) Bruce], letter, 11 July 1915;

3. In which case, maybe Will should be in quotes:

[William Robert Bruce] “Will” (In the field) to "My own Dear Wife" [Ethel Sarah (Phelps) Bruce], letter, 11 July 1915;

4. (This one I like best) From EE QuickCheck Model, EE, 3rd edition, page 109 (Kindle):

William Robert Bruce (In the field) to "My own Dear Wife" [Ethel Sarah (Phelps) Bruce], letter, 11 July 1915;

5. From, "A Dozen Conventions You Want to Know About," blog post, 31 July 2018:

William Robert “Will” Bruce (In the field) to "My own Dear Wife" [Ethel Sarah (Phelps) Bruce], letter, 11 July 1915;

Finally, according to his diary, “In the field” was Abeele, Belgium, near the border with France. Am I correct in thinking the location should be included in square editorial brackets?

…(In the field) [Abeele, Belgium]…