There are better makes – I’ll have a look in the van in a bit – just can’t remember the manufacturer.
On the sinking thing, there is a solution (of sorts). Do you have a foam gun? i.e. expanding foam cartridges with a gun that’s removable? If so, you can set it to a very small flow and fill the gap to just below the top of the skirting. Wait for it to cure and then caulk. Gives the caulk less room to sink.
If you’re not experienced using foam, then have some of those citrus wipes handy for accidents…clean up straight away. If you don’t have wipes and mess up, let the foam go off before removing 🙂