Optic suggestions for an AR pistol with CASV?

[Diamondback]

EDIT: TL-DR: Looking for optic-mount combo suggestions with a focal height in the 24-26mm or 28-30mm ranges.

Application: Weapon is a pistolized Mk 18 Mod 0 EOD, with Vltor CASV-EL rail.Intended use is GHB/Briefcase/Discreet Carry PDW, something to give an in-between option between a sidearm and a full patrol carbine. (*I* will probably only ever use it as a GHB, but I'm trying to design and build to a standard fit for Undercover or Stakeout Duty--a number of friends are Active or Retired LEO, and my "build finished" standard is "would I be comfortable with them taking this out for duty?") Expected engagement range no more than 300m, mostly urban/Close Quarters. Primary requirements are discreet and rugged--as something that'll live in a Go-Bag fulltime with other heavy gear, the optic will need to take a fair amount of knocking around. Discreet, I'm not sure which would be lower risk of a "YO LOOK GUN HERE SHOOT THIS GUY FIRST" print between the corner of a pistol-size mini-reflex like a Docter or an RMR or the longer but more gently rounded tube of something like an Aimpoint ACO or PRO--CompM4 means obvious extra bulge from the battery compartment, ACOG ain't happening and is both outside my budget range and overkill with all its drop-compensation. Probably also too big and too high for CASV compatibility.

I've found a few options starting from factory mounts that look like they'd work as possible options, but haven't really waded into aftermarket mounts yet building my spreadsheet, so I thought I'd ask you guys for recommendations on four scenarios trading up from "Starter" to "Value" to "Better" to "Best." "Starter" would eventually be consigned to range use only on another build, something like a Bushnell TRS25, "Value" being a little higher but still moderately priced, a not-first-choice-but-pretty-good-for-the-price. "Best" would be like Trijicon or Aimpoint CompM4 level. "Better" would be maybe not Mil/LE Issue, but something where if your Top Tier choices were off the table you'd consider it an "acceptable in-a-pinch substitute"--better capability/quality than Value but better price than jumping straight to Spare No Expense.
[moving identified viable options list to second post]

Try to go easy on the virgin, please... If you were attempting a build with these constraints, how would you do handle the optics? ("Bare Irons Only" is an option too, but the BUIS is one more thing to remember to pop-up and there's already the buffer tube to unfold in deployment.)