I can't do the first metro kingdom skip consistently (the first jump after you get down to the mainland, where you bounce on that curtain thing) so I decided I'll go around the normal way. But I need 1 more moon because I don't get Girder Sandwich. I figured I'll take Captain Toad. Is there a faster alternative?

how long have you spent practicing the skip?

honestly just practice the skip. you'll be much better off with that than without doing the skip. if you really dont want to do that though then just get the girder moon after you get to the stairs normally by either using the tank to bust down the arch or just cap dive over.

you can do it an ezier way by slowly climbing via various platforms but

1. it's slower (and like 20 if done quick)
2. You would have to go a little bit back after you reached the top to get the power moon I do this but I don't recommend it

The skip is really not that hard, just practice it a bit. It is still faster to fail like twice at it than going around that stuff.