On the rise to high krausen the Westy clone will tend to get metabolically hot due to the extremes of pitch and abundance of food. We think the ideal is to keep it in the 77-80F bracket (at the height of krausen). Allowing it to get hotter up to about 82F will still work but lower seems best if the pitch is healthy and adequate. Absent a jacketed fermenter you can use a fan on small stainless fermenters to gently control the temp rise. St. Sixtus uses water cooling, (they have the same challenge).
On the opposite end, if the primary drops below 70F too soon for any significant time we've seen Westmalle fall asleep and slowly eek out a bubble or so for many weeks and languish. It still eventually reaches FG but it's painful to watch
and not the ideal ferm schedule.
Having plenty of fermenter headroom for the top-cropping and explosive rise of a healthy pitch is also helpful. In our 17.5 gallon conicals we ferment only 10 gallon batches, (43% head room). Even with this we still get blow-off.
We haven't tried open fermentation due to a lack of a PV, hepa filtered. double door sealed room. Fantastic next step though if I could get the company funding approved to do it