Pagnr, could you tell me which spray nozzle you've found most useful for reaching the underside of leaves?
Using a small 10 litre sprayer with a pumped handle to pressurise, pretty common type.
I found it most useful to have an extension to double the wand length and/ or also a longer hose from the tank to the wand.
It makes it easier to wave around, and also not move the spray tank so much, or have to lift it.
Also an elbow bend on the nozzle end, easier to point upwards.
If you can adjust the spray pattern of the fitted nozzle to a wide fan, that can make coverage easier without having to look too hard.
Irrigation mister nozzles can give a wide fan, with less spray volume used. Might need an inline filter fitted to stop clogging the finer nozzle hole.
Or be careful when mixing to strain out lumps, and shake tank to prevent slugs forming.
Brass nozzles on screw threads can be fitted to the plastic nozzle on the sprayer.
Not sure I have seen Thrip larvae moving much, seem to cluster under the leaves on the main vein. Infested plants are often silvery looking from the feeding activity. Adults and larvae were present at the same time. However there are a lot of species, so couldn't be sure they all behave like that.