I think the most important number is how much full-timing cost are different form S&B costs before full-timing.
For us - we dropped $1,732 per month on average for the ten months of full-timing.
That was almost all related to the expense of keeping a 2,500 sq ft home.
One item - internet data access - is $53 per month higher for less data than we had previously.
Our expenses for things like food, entertainment, clothing, cell phones, etc - have not changed.
We spent $2,639.97 on campground costs last year (2014) for 132 paid nights of camping. An average of about $20. We volunteered at a national park and a state park for the rest of the year. We traveled/ towed 6,586.7 miles for a cost of approx. 2,480.9 in fuel - $0.37656 per mile.
We spent approx. $865 on direct expenses for the trailer - upgrading the microwave, adding some things, etc.
So - we saved $17,320 in expenses for 10 months of full-timing.
We spent $530 of the savings for internet, $865 for the trailer, $2,639.67 for camping costs and $2,480.29 for fuel - a total of $6,514.96. Which turns into a net decrease in cash outlay expenses for 2014 over 2013 of $10,805.04.
If we had paid for camping rather than volunteer - that would have been about
$3,480 in other costs, and say $1,200 more in towing fuel. Which would have resulted in a net decrease in spending of about $6,125.
Yes, traveling actively and staying for only a few days is more expensive. We are in such a mode right now, and have to watch the penny's on food, cutting back on eating out and entertainment costs.
We will be at our volunteer location from mid-April to mid-October - where we will not be paying for camping or towing costs.