I’ll add a non-technical answer.

Insure them for the cost of each full replacement HANDGUN, at whatever price you feel comfortable being reimbursed if they get lost or destroyed. You will be paying for the insurance coverage, right? Who is the USPS to tell YOU the “value” of something that they wrecked or lost if you paid to insure it at $X.xx amount?

I certainly don’t think you are odd for being apprehensive, but most of us ship whole firearms around the country and it’s just part of the game. Unless you are really bad at packaging something up, your two slides aren’t more likely to get lost or wrecked than the countless full guns many of us are shipping.

I would much rather let Trijicon do their magic and not move any fixed sight unless I really (really!) need to.