As it happens, the barriers aren't in use yet, but on the west-bound ale trail the barriers don't have any impact. So, unless there are manual ticket checks, it's straight off the train and into the West Riding. Similar at Huddersfield and Stalybridge.
At Huddersfield the pubs have less of an impact than you'd think: The Kings Head platform door is usually only available for those unable to use steps, and at the Head of Steam many of the staff will be suitably frosty with anyone they suspect of using the pub as a way to avoid ticket checks. Clearly the licensees don't want to create unnecessary friction with the railway.
The West Riding at Dewsbury is more of an issue because the doorway is more visible and less foreboding. However it's in Dewsbury, so most ale-trailers won't actually leave the station at all. The pub is more likely to be used as an 'escape route' by regular travellers without tickets than it is the ale trail crowd.
A large majority of the ale trailers start their trip at Victoria an so they do all have tickets. I know they do as I'm the one selling them an they do all pay. They moan about the cost, but they do pay as they can't get on otherwise.
Even those starting at the other end will most likely start at Leeds which is also gated. Some at both ends might try short-faring (a ticket to Batley or Stalybridge when they're in fact doing the whole run) but ticket checks on board are likely to catch these people at some point.
I did once board a train at my home station of Batley along with a group of quite loud ale-trailers, and when the guard came down to check tickets one of them had only a Leeds to Batley CDR. When the guard queried this (he asked if he'd been using splits, even though I don't think there's a split saving to be had, so I assume he was just avoiding confrontation) the bloke just looked a bit confused and squiffy... but far from becoming aggressive or abusive towards the guard as I expected, his mates instead took the Mick out of him for trying it on! I didn't find out what happened, the guard may well have just sold him a regular ticket as a goodwill/conflict-avoidance thing- but it goes to show that not everyone thinks that getting away with it is okay.
