I got the plates from Sure Plates and they came with, I think, 15 (short) number plate 'height' size double sided sticky pads (and various screws and white and yellow screw covers)
I just used the supplied pads and they seem to have done the job. I've driven in hard rain (well you know what the weathers been like!) all day today and they are still firmly attached. If I recall, I put about 8 on the front (all vertical) and 5 (or 6?) on the rear; two vertical spaced out at the outside edges and one horizontal, on the lower part of the plate only (there is a big recess in the bodywork at the top behind the plate at the rear).
I cleaned and dried the area (body AND plate) with alcohol wipes (actually I took a shortcut and used hand sanitiser on a bit of kitchen towel, as I was in a rush
)
I'm not sure if there is an answer to 'sticky enough that will also come off again in a few years.' You want them to stay on firmly so that they can't fall off or be stolen easily but yeah, at some point you might want to remove them.
One word of caution is; the back plate at the front. If anyone is going down the 'stick on vinyl number plate' route, on my MY, it is attached to the front bodywork with some strange looking 'super fastener' ~ obviously designed to not come off easily. I think you'll need a mole wrench to undo that. I couldn't work out exactly what type of fastener it was (and honestly didn't look too closely). It almost appeared like it was attached and then 'melted' into position ! Good luck with that one.
The front back plate is also curved slightly which doesn't lend well to attaching a rigid plastic number plate but the number plate seemed to have enough flex in it to stay in place with the supplied pads. Also the backplate isn't as smooth as the bodywork on the rear, so I was a bit unsure if it would actually stay in position, but so far so good.
Oh yeah, and the 'Tesla' black 'boarder' plate holder wasn't centrally mounted on the backplate either, so be careful with the positioning, don't measure off that, assuming its central.
There are some good vids on you tube about how to do this.
Long ramble... but if you don't get any pads supplied with the plates try Halfords or you can buy them on Amazon.
Cheers and good luck.