I'm almost positive I took the gas tank off also when I changed
my plugs. It's a pain in the arse. I think it was one of those things
where it made it easier with the effort to remove everything then to
keep trying to weasel around stuff.
I remember trying to get the one spark plug boot back on
the one side was even more trouble. For me that is.
The only thing good is, the more you take it apart, the easier it gets
putting it back together. Plus when you take the body parts off, you get
a good look at other stuff that sometimes takes your attention away from
what you originally set out to do
PS. I too was afraid of dirt falling in the plug hole. I just used my
compressor to blow out around the plug first & hoped I got it all.