https://www.youtube.com/watch?v=g6luPxbODw8This kid showed me that particular how to do the valve stem trick, and it works as advertised
You lightly air fluff the tire once to take out any fold over wrinkles, then take the core out completely during mounting as no air pressure is desired during mount (you'd just have to fight against it). You fluff it once more for good luck to pull any tube wrinkles out of the junction between the lips, then you pull the core and retighten the zip ties because they likely stretched a tiny bit during the fluffing.
No core in place during the actual mounting / wrassling and
you should use enough zip ties to keep the tire from gaping open any at all in the zone up where you are using tire irons.
I tied a string around the valve stem and used the string through the hole to guide the stem to hole mate up, which was fairly easy to do. You have the stem in the hole and the nut turned in place a turn or two before putting the rest of the tire into the rim well and getting out the irons, working on the wheel side that is opposite the stem.
(I mean if a 10 year old kid can do it, I should be able to do it even as I get older and weaker -- very encouraging to me, really)The needed 16" or longer zip ties are HUGE and a small flat blade screwdriver can hold the zip ratchet up out of engagement (tug hard while inserting the thin flat tip at the ratchet paul edge) so I was able to recover the big zips ties to use on my next tire.
Now, having been told you can guarantee you won't pinch a tube and you only have to fight one bead, who wouldn't like this method?
My old batting record for brand new pinched inner tubes was about one tire in four.