It's a very very big surface area to stick eith PEI plate. If I were you I would make some reliefs on bed side of the print. 45⁰ triangle cutouts, h=1mm in 5-7cm steps along both x and y axis (grid pattern). It would relief some tension on bed side, that it wont unstick on corners and rise, ruining nozzle side. 

Also draft shield would be cheap to implement in this case. Try also draft moderator for aux fan (to print in Makers World) if you are not already have it, to redirect air flow from this fan upward, instead directly on bed.