I'm an engineer-type, so I do tend to count & measure things, but I have not found it all that useful to keep a log of motorhome expenses. Of course I have a pretty fair idea of the annual repeat items, e.g. insurance, tags, and oil & fuel filter changes, but travel & camping expenses vary a lot, and my expenses are unlikely to be much like yours, for a host of personal choice reasons.
Part of the reason we don't track closely is that we would probably be appalled by the expense and quit the lifestyle!
You can guestimate campground expenses as N nights x $Z/night (you make the estimate for your needs). Fuel is M miles/month x $D/mile (probably about $0.30 mile right now @ 7.5 mpg). Entertainment expense (tours, museums, souvenirs, whatever)? Meals out? Your call.
Maintenance is planned stuff like oil changes, but it gets complicated to fill in stuff that runs over multiple years. Tires, air dryers, coolant changes, etc. Lots of stuff like that on DP, and each coach may have different intervals and needs.
Repairs are unplanned stuff, thing that break. I figure it's a good year if I don't get hit with a $1000-$1300 bill for something, but it doesn't happen often.
There is an example of fulltiming expenses in the Library that may give some insight. See
http://www.rvforum.net/joomla/index.php?option=com_content&view=article&id=219:fulltiming-expenses&catid=29&Itemid=132