No worries man, I can totally understand your frustration, I have installed car radios, amps, and capacitors since I was a teen, granted only on occasion for friends, and for my own system that I had, I sunk 8,000.00 into it, so it was a lot of work, with occasional frustration involved.
The 10A fuse definitely won't be enough, even a 20A would be pushing it, at minimum I'd go with a 25A to 30A one.
I have been searching for a few minutes now, and so far I cannot find anything higher than a 10A fuse tap, however I do not see why you could not get the 10A Fuse Tap Kit, and use a 30A fuse in it, the distance of the wire you will run to the radio is short enough that the same wire should handle the amperage, as long as the wire used from tap to radio is 12-gauge, and also the wiring coming from the tap, which I am almost positive that is the size of the wiring on most of the fuse taps.
If unsure before buying the fuse tap have them verify it is 12-gauge, the 12-gauge will handle up to 35A.
Just try to keep the wiring from tap to radio around 4 feet at max, any longer than that and you will want to go with a 10-gauge wire, which I don't think those kits have on them.

agreed, the fuse panel should only be a couple feet from the HU and most aftermarket HU'* draw most of their power from the always on supply, so may not even be 10a.

I thought it was the other way around? On switched power, the HU used most of the power from that line, but with always ON power, it only used power for its internal clock?? Thus to prevent battery drain?

it has internal switching to turn the amps on and off like anything else but there are a few of the higher power ones were you end up running a bigger always hot wire. the sony i put in my yukon needed one it kept cutting out