You don't need to touch the tank at all to change the plugs.
Just go easy when doing it, try as much as possible to undo and tighten the plugs with your fingers, and keep the plugs upright, don't hang off them sideways with a socket and wrench or whatever you use.
Before undoing you should really use an air line or can of air and blow any crap away from around the plug area.
You'd be surprised how much shite gathers around the plugs over time and once you remove a plug the first place this said shite is going is downwards.
This is not good.
You don't want it in your engine so a good blast of air is always a plus.
When putting new plugs back in, tighten up as much as you can using fingers, to avoid cross threading, then idealy they should be torqued up to avoid under or over tightening which can cause all sorts of bad news.
Do not use any anti sieze (copper) grease or lube, it's not needed at all as the coating on the threads prevents corrosion, plus your torque settings will be totally wrong.
