Regarding tire liners:
I only have experience with the Slime brand ones.
What I usually see with them is that over time, they move around in the tire, creeping up the sidewall of one side in one area, and up the sidewall of the other side in a different area, so they end up kinda like a squiggle roughly centered on the tread area, and don't actually protect you from flats very well.
This happens more often and is worse the lower the tire pressure is, and the wider the tire is.
The narrower the tire and the higher the pressure, the less of a problem it is.
Heat makes some difference too--the plastic of the strips deforms easier the hotter it is. When I used to ride regular bikes, the liners would be ok in the winter, and mostly in the spring and fall, but in the summer they'd have to be realigned sometimes. If they got too distorted I'd have to get new ones cuz they wouldn't straighten out. I'd know when this was necessary because I'd get flats or slow leaks.
After realizing the pattern I would check them in various conditions and find them straight until temps started staying over 100F+ much of the day.
Riding with just me on there it wasn't as big a problem, especially back when I only weighed 120lbs or so. If I carried cargo regularly when ti was that hot, it got to be more of a problem.
What I do now when I use them is use the liners between an old thickwall tube that's slit along it's inner circumference, and the tire. The actual inflated tube goes inside the slit tube. It doesn't seem to make that much difference to the squiggle problem, but it does keep the liners from ever cutting into the actual tube (which is an occasional problem), and it adds one more layer of flat protection for short objects.
One thing you *don't* want to do is glue the liners down. If they are fixed to the inner surface of the tire, then they won't move to let stuff slide across their surfaces and deflect the points away from the tube, or let them push inward, and the stuff will instead puncture the liner and your tube.
I know this because I tried adhesives including flexible silicone to glue the liner to the tire, and that's the only time I ever had punctures of the liners themselves (except for once when I had no choice but to ride thru a bunch of roofing nails falling out of a truck further up the road--Slime did replace the liners and the tubes when those nails went thru, per their guarantee, but I still had to deal with the flats in the heat at the time).