A & C
If you are breaking even on 80 hrs pa you are doing AMAZINGLY well, I have worked it out before and reconed 200 - 300 hrs is nearer the mark if you include things such as depreciation and engine replacement costs.
Add up your Fixed costs:- depreciation, insurance, parking, hangarage, and fixed maintainance, divide by your expected hours and you will arrive a your FIXED operating costs, for something like a PA28 I would be surprised if this was less than £5000pa, which on 80 hrs pa = about £80/hr, then add in your D.O.C.s (Direct Operating Costs) :- engine replacement costs on schedule, fuel, oil, maintainance (if you go above 50hrs) and you are getting to about £120/hr and have allowed NOTHING for any additional maintainance snags. (I can hire a pa28 for £85/hr)
You can of course reduce this if you have a freindly farmer who will lend you a field, but I still think 80 hrs would work out far to low to break even.
nb. if you are getting reasonable utilisation it is now not much more expensive to operate on public transport than on private.