I would say as you get the 60 days on entry the best and cheapest way is to just then do a border run and get the additional 60 days so more than your intended 102.
Don’t do an extension as you’ll only be at 90 and therefore still need to do a border run as have paid the extra 1900 for nothing whatsoever
Wise without doubt is the easiest and usually the cheapest way. You will get the odd person who likes to just rant around but generally wise is the best.
I pay about 2000 baht a month for electric and 200 a month for water that’s what I’ve been paying pretty much for the last 4 years living here. That’s a 84 Sqm condo so good size. You don’t need to sleep with ac on a good fan is much better for you and your bills in any case