Powernumpty

Now that is after sales service.

I stuck a whip up becasue I thought the Mag Loop noise level was a little better than I remembered, turns out the loop is still covering an horendous level of switchmode noise that I just can't handle with the whips.
I tried double copper shielded coax, Cat5 with baluns (worked before but this run is longer), lots of ferrite and earthing but everything I did pushed the noise around, reduced in parts but nothing made it useable.

I've got a portable spot I want to try a whip but in my short garden or close to other kit just waste of time and effort (for me).

On the power supply why not try one of the DC-DC step-down's mentioned on the forum, linear on the input side, surprisingly good.
That said here the general switch mode junk is so bad with a whip and and Kiwi on linear supplies it still picks up every switcher to the next county.
I'll stick a second kiwi online to compare "Loop to Whip" if anyone wants to see a real-time comparison.

"I'm wondering if the kiwi will be able to handle it" I'm pretty sure downconverting that range has a lot of other VHF (+FM broadcast) mixing stuff to reject so filtering is important before and after the conversion, The Kiwi is just excellent test kit showing up any failings and mixing products.
Admittedly I was using one set up for 2m so birdies in the airband may have been intentional to keep them out of the required band.

Does make me yearn for a version that does 32MHz of VHF/UHF or even a modular one, lots of rf boards are being sold for self assembly RF chains.

The LZ1AQ amp will work as a simple dipole, I think the balanced antenna may be easier to get working and I'm a real fan of CAT5/6 shieled feeds for RX antennas now.
Mine is two loops with extra vertical sections and it is more sensitive in the vertical dipole mode but also more prone to the local noise.

I also have an Aerial-51 Model 404-UL, that I keep meaning to put up somewhere (when I win the lottery) virtually invisible wire, they do heavier versions that cover 80m. The thin wire on the UL is probably not suited for permanent installation. I'm not sure if your wish to avoid the wire is visual impact or something else?

You need a nice old linear to feed a mini whip. Check it gives the required voltage at the right load, some 12V will be 18V off-load.

There will be pick up on the feedline, it needs to be halted and/or fed to ground at the most affective spot(s), that is where the fun starts.
At the very least see the outside of the coax as a likely source of trouble from common mode signals, break it up (in common mode terms) and ground it out.