Plasmonic structures can provide deep-subwavelength electromagnetic fields useful for enhancing light-matter interactions. However, because these localized modes are also dissipative, structures that offer the best compromise between field confinement and loss have been sought. Metallic wedge waveguides were initially identified as an ideal candidate, but have been largely abandoned because their experimental performance has so far been limited. We combine state-of-the-art metallic wedges with integrated reflectors and precisely placed colloidal quantum dots (down to the single-emitter level) and demonstrate quantum-plasmonic waveguides and resonators with performance approaching theoretical limits. By exploiting a nearly 10-fold improvement in wedge-plasmon propagation (19 µm at a vacuum wavelength, λ_vac, of 630 nm), efficient reflectors (93%), and effective coupling (estimated >70%) to highly emissive (~90%) quantum dots, we obtain Ag plasmonic resonators at visible wavelengths with quality factors approaching 200 (3.3-nm linewidths). As our structures offer modal volumes down to ~0.004 λ_vac^3 in an exposed, single-mode, waveguide-resonator geometry, they provide advantages over both traditional photonic microcavities and localized-plasmonic resonators for enhancing light-matter interactions. Our results confirm the promise of wedges for creating plasmonic devices and for studying coherent quantum-plasmonic effects such as long-distance plasmon-mediated entanglement and strong plasmon-matter coupling.