Im no expert and would love to know if any of what im saying is wrong.
As far as i know the best thing to do is keep them around 25C or even a bit less and at a stable temp. Im using a mix of 50% oven dried pearlite and 50% water this season, i have found this works well with spencers monitors so im hoping will also go well with these guys(both take 3-4 months to hatch). Last clutch i had most of them died, i was using the over water method but i think i let them get a bit to hot and i was using ice bricks to keep the temp down as they were inside and room temps got to 30 on many days. I think the over water method would work fine and was more likely higher temps that killed them.
In a dry environment they die very quickly, i experienced that a fair few times when i took a few days to find the eggs. Northern types may lay all year round although i dont know much about them and havnt got any good eggs from my goldens yet.
So in short you want to stop them getting too hot and keep temperatures as stable as possible to avoid conensation or drying. Putting them in an insulated area under your house would probably do the trick.
They will also lay 2 clutches a season, so you may get more in a few months.
Here are some pics, good eggs, some slugs/infertile eggs and a good egg a few weeks old being candled.