Is there a way to string or tune a piccolo guitar (the Ibanez ewp32 in particular), which comes tuned in A naturally, be tuned to standard? And would that increase or decrease the string tension? I learned chords for a classical guitar ages ago, so I'm learning again from scratch (which means it'll feel normal to me if it works!)... and I really want to be able to switch easily to a baritone ukulele, and also don't want to start out finding/understanding the tab, etc. for non-standard tunings... Also, are all 6-string baritone ukuleles or "guitarlettes" tuned up to A, because I was assuming they were standard while I've been shopping... Thank you!
I can answer some parts of your question.
Tuning a piccolo guitar, which sounds higher than a guitar, down to a guitar would decrease the string tension. It's therefore not going to cause issues with string tension ripping your guitar apart or anything, but the strings might be slack and rather unplayable. Or maybe it'll sound fine; I haven't actually tried this. Point is, not going to be a problem with string tension.
Are the baritone ukulele and piccolo guitar compatible? Well, the baritone ukulele is the highest-pitched strings of a regular guitar, and a piccolo guitar is like the guitar has a capo on the 5th fret. A piccolo guitar's highest 4 strings are like a regular ukulele's strings. Put in an intelligible format,
- To play something on a baritone ukulele that you can play on a piccolo guitar, put a capo on the 5th fret of the baritone ukulele (you won't have the two bottom strings because ukuleles have 4).
- To play something on a piccolo guitar that you can play on a baritone ukulele, put a capo on the 7th fret and play on the 4 highest-pitched strings (you will be playing one ocatve higher).
Absolutely zero baritone ukuleles are tuned up to A. Baritone ukuleles are tuned in G (be careful; we say guitars are tuned to E, but baritone ukuleles are "tuned to G" because the open strings make a G6 chord). Baritone ukuleles are tuned the same as the highest 4 strings of a guitar, and all other sizes of ukuleles are tuned to C, which is the same as the 4 highest strings of a piccolo guitar (even though we say piccolo guitars are tuned to A).
I've never heard, and hope I never, hear, anyone call a baritone ukulele a "guitarlette".
The answer is yes, with a little effort.
Of course, you can just loosen all the strings to pitch, but that would not give a very playable instrument. There is a better way.
The instrument already has an A, D, G, and high E string, and the C string can easily become a B string. The problem is they're all in the wrong place. Restring your instrument with all the strings one over. You may need to file out the nut and bridge slots to fit the strings.
Now, the only thing left to do is get a low E string. Ibanez's piccolo strings are sized .010p .014p .023w .030w .039w .047w. Let's pick something comfortably larger to be our E string. 0.56 sounds about right.
Side note: Your intonation will be a bit weird with this setup... There's a good reason "real" guitars are not this short.