

Planning on pinning my first moth - bought a kit but would like advice
Pics of him still alive as bug tax (if anyone would like me to remove the full body photo of him due to visible goo just let me know)
Hello! Sorry if this is rambly - I'm not a reddit user so apologies if this is improper etiquette. Pinning is something had an interest in for a while as a massive bug lover. At my job (a gas station of all things) the lights are unfortunately left on at night and when i come in during the day theres frequently dead or dying moths that got left behind when day came. Ive always admired them and then set them aside to decompose naturally, but I've always had the idea of collecting and Pinning them - an "imperfect specimens" collection showcasing the wide variety of species ive found there that I'd never seen in person alive before, all collected from my job, but I never actually got around to looking into it.
However the other day I came across a gorgeous male Polyphemus that was still alive but mortally wounded - likely hit by a car or dropped by a bird since he had external damage. Such a massive moth in my area is a rare sight and is what motivated me to finally take him home and give it a shot. He was still alive but barely when I got home and I transferred him to a container and frozen him so he could finely rest (it felt really bad - moths are some of my favorite animals, but one of his lower wings was literallt glued to his abdomen with his own guts and his intestines were hanging out his rear. He was not going to survive.)
I got a pinning kit and it should be here in a few days, hes in an airtight container in the freezer now as I wait, and ive found myself wondering - the kit is coming with size 2 pins, but I'm worried that those might not actually be big enough for such a larg bodied moth? Should be fine for the actual holding down the wings process of course, but for the abdomen.
Also, he has a spot of gut goo on his back from his injury, its dried down/frozen at the moment so i doubt ill ever get it All off, but any suggestions for removing some without doing too much extra damage to him? Im bound to make mistakes early on of course, which is why using naturally found imperfect specimens kind of removes some stress. Poor fellow is already missing a lot of wing scales with some see through spots, but i honestly think that makes him more interesting than another perfect moth. He has a story.
Another question - and this one is kind of stupid, but I know during the pinning process you pin through the torso itself, but in most people's displays there's no visible pins afterwards, how do people mount the bugs to their display boards with no visible pin?
And one more - if I wanted to make a display look nice by covering the foam with a piece of fabric, are there any materials I should avoid? I plan on using silica packets in the frame of course. Anyway. Thanks for reading rambling disaster of a post, thanks for any help!