OP - Sorry to be late to this thread, I've been travelling.
Some considerations. I think I remember that you are in coastal SoCal. Moving 30 miles inland is an entirely different climate. Your AC and Heat bills will be impacted. (I'm coastal San Diego and we don't have AC - and there are only a few weeks a year, recently, that I wish we did.)
Also - if I recall - you have young children at home... so a small house has to be laid out right to work for a family (vs. a couple). You'll want some room for kids play area.
As you mentioned - commute is also a factor. (You're on sabbatical now, right?). Check google maps to see what rush hour commutes are from your inland location to your job. My goal was to have a commute of less than 30 minutes. My commute was 6.5 miles - and towards the end of my working career - that was taking 45 minutes or more due to gridlocked freeways and surface streets.
This is not to discourage you - but, rather, these comments are to add thoughts to your plans.
We live in a 2k sf house about 2 miles from the beach (3 miles by car). So we get the coastal overcast in the mornings and evenings that keep our house cool/moderate year round. We have good friends just 15 miles inland from us and they regularly get temps in the 100's in the summer, and frost in the winter... their utility bills are orders of magnitude larger than ours.
IMO - for a family with kids - minimum size is about 1600sf. But I don't see a lot of value in going above 2500sf.
But - yeah... having no mortgage payment is VERY liberating. Our annual spend is significantly lower now that the house is paid off.
Retired June 2014. No longer an enginerd - now I'm just a nerd.