Preparing yeast for secondary fermentation

I have a barleywine in progress that seems to have stalled around 9% ABV with some residual sweetness I'd like to try and reduce. After 2.5 weeks in primary all activity had stopped so I racked off to fresh fermentor. Two more weeks with agitation and SG hasn't really fallen any more.

I'm thinking of pitching Safale US-05 to see if it can drop it a few more SG points. I've found little advice on how to prepare yeast for such a toxic environment. This comment in a post about preparing a starter argues it's a pointless exercise as only 'unhealthy' yeast will result from highly alcoholic environments. Sounds a bit wonky to me - I'd expect unhealthy yeast to die and the survivors to be more resilient..

My own idea would be to rehydrate as usual in ~25°C water for ~15 mins, then slowly add barleywine over another 30 mins or so to gradually bring it up to 9% before pitching. Seems more likely to give them a chance to adapt than by pitching straight from being rehydrated.

All views on this from those with relevant experience very much appreciated.

Edit: Details of (slightly experimental) recipe. Batch ~15L approx - all quantities are estimates as I used the parti-gyle split method..

Mash - 60 mins @ 67°C (target temps hit)

• 5.0 kg Marris Otter Pale
• 0.2 kg Crystal 120

Boil additions

• 0.1 kg roasted barley ('tea' from cold steep)
• 0.5 kg light DME

Nottingham yeast

OG 1.083 | FG 1.016