Ummmm, no. That's like saying TP Link's true form is a wolf. Because he is now dead OoT Link does not have a physical form and so in the physical word he assumes the form of a wolf. However, when in the dreamlike after-life realm he can assume his 'true form' which is the form perhaps of a stalfos (maybe Link got lost in the woods and turned into a stalfos), or his skeletal form is simply his bodily remains as they would appear in the real world. To say the Golden Wolf is his true form implies he fought Ganon and journeyed to Termina as a wolf. Which he clearly didn't.
How in the world does that imply that he went to Termina as a wolf after possibly several hundred years have passed? I mean, honestly, many things can happen in that timespan. Also, the Golden Wolf could very well be his true spiritual form, as it would coincide with his spiritual successor's - TP Link's - wolf form, which was brought upon by divine influences and the mark of the Triforce, to protect him from the negative influences of the twilight veil; there isn't very much to dispute this.
Also, the Hero's Shade is not a Stalfos. I mean, if anything, his
face might appear somewhat skeletal, I'll give you that.
However, his body appears to be made of a more ethereal
ectoplasmic substance than anything; it is very ghost-like in nature. He even has muscle tone for Pete's sake. (lol)
There is very little to suggest that he got lost in the woods for all eternity. It is more probable that the armor that he wears is the armor of the Hylian Knights of the era in which the Hero of Time perished; this would coincide with the similar design of the armor worn by the Hylian Knight spirits in the castle courtyard (they can be seen by using the wolf senses). For all we know, the Hero of Time could have returned to Hyrule after his exploits in Termina, and became a knight of the Royal Family.
There are many other skeletal [skeletal-esque] beings in the series - many of them are members of the -stal family -, but they are
not Stalfos'. Igos du Ikana from
Majora's Mask comes to mind.