Dont know how long you intend on keeping it. But here is my .02
5 years or more.... RST order, yeah the idea of buying the Premier and trading in isnt bad but taxes etc you will get your fudge packed for about 5 to 10k I think depending on your states tax laws etc.
2-5 Years
Get what you can actually get right now. Make it yours... Instead of silver trim over the grain, Id suggest something like black chrome wrap or body color. Wraps can be removed so when you sell its stock as build sheet and you get a few hundred more.
Exterior, wrap or exchange to get the blacked out look your after. You can buy the RST grill OEM and swap it, wheels easy swap at dealer. Mirror caps as mentioned above.
I think you get more out of the premier trim than the RST bang for buck since most RST are LT trims upgraded. If you love the RST badge. Do the work and put the RST badge on there too.
All in all, sometimes making your ride what you want vs what the factory packages can give is rewarding, sometimes cheaper, but alot more fine tuned and you stand out from the crowd etc.
All on what you want and evidently your not pinching pennies here so two roads... Premier it and make it yours, or order what you want and get it in a year. If worried about interest rates then Id suggest grabbing that Premier now. I got my Burb Last sept at 2.85%, they are raising interest rates to curb inflation as we speak so do what suits you best and your family man.