I somehow missed this thread earlier it seems! Welcome Icminis, tho sorry to hear the circumstances of our 'meeting'.
(Surprisingly) I agree pretty much with Trinity. Except that I differentiate sole with lamellar wedge material, so I would say that bevelling back that far is NOT invading the sole anyway. The sole grows from the base of P3 & anything outside that border is not sole. *However if this horse has had long toes long term, it's possible the bone &/or corium has remodelled into a 'ski tip', meaning it is further forward than 'normal'. But I believe Trinity's lines allow for 'margin of error' so that's pretty much by the by.
Reiterating I know Saddle, but the big 'drastic' thing about that foot - right looks worse than left is the extremely long toe. That will be putting strain on the laminae, the dorsal aspect of the distal interphalangeal joint, the coronary artery, DDFT and navicular region. Removing the excess will do nothing 'drastic' aside from relieve a lot of those problems. As Kyella said, when we get worried about tendon strain is when lowering high heels or otherwise changing angles too much/quickly.
On the subject of hoof hardeners, I don't tend to think much of the idea. The soles, no matter how hard they are, if thin, still won't provide much protection on hard/rough ground to the internal structures. For that, they need to *grow* thicker. Hardener can also make keratin brittle, so more likely to crack, less flexible. I have not personally looked into the effects of chemicals such as formaldehyde on living tissue, but it is permeable to skin(would include sole but not outer walls) and considered highly toxic. That Dr Bowker & others I respect have looked at it at cellular level and deem it unfit for a horse's hoof(a live one anyway!), especially frogs, is enough for me.