It is blindingly easy, but board specific to make this work.
The easiest option is to gain a card mid turn. Count, Iw, Wshop, Magpie ... basically anything that does not gain to hand or deck top will work. Yeah you have to play the gainer before you have <3 cards in deck ... but that is basically just an extra village to carry around and normally the right call if you are using gainers in general. Running double gainers (e.g. Iw + Count) basically assures that some of your Swashbucklers hit.
Slightly less easily you can discarders - attacks, Cellar, Inn ... again the only real challenge are drawing the enabler early enough and having enough villages for terminals.
Top decking also works great. Gain a Swashbuckler mid shuffle with Tracker, play and forget. Use Count/Scheme/Etc. to play it on a hand in the middle of the shuffle. Not so great, but fun when you can manage it is to top deck 8 cards with stuff like Haunted woods, Alchemist, Kc/Count, etc.
And if you just want the Chest, then any other coffer gainer works wonders.
Sure, 100% reliability is hard. But we are talking about coffers. Smithy with half a coffer is still a strong; Getting chest on a lot of boards is just utterly overpowering.