Bill I would be interested in your response after doing your volunteering.
Give others your perspective of what you did and also who supplied the labour (age groups and areas represented etc) and the response you see from the so called charitable organisations that advertise the most for money.
I think many of us should and do offer our time as we travel as it makes the journey more interesting and gives you a purpose to your travel.
I might be different to many as I am homeless and loving it so I can go where I desire and I try and spend one month every three months doing something where ever I am.
There a charities such as Blazeaid which we worked with during the fires and also many local organisations where you can fond someone who would appreciate a hand.
Many Farmers etc love to have someone different as company for short time and often it is mainly for company but you can assist with many small jobs that are just too hard for one person but for us travelers is not work but an experience and is usually accepted with many thanks and offers to return whenever in the area and often rewards you are not expecting.
I have one farmer who I swap a weeks work (general farm work painting etc) for a week on his private house boat on the Murray and it is absolute bliss when you live full time in small bus.
Even though I have skills I often find that it is just passing things up a windmill, fencing and general odd jobs around the farm that they want. Things that cost a fortune to get done IF they can.
I have a station that was being charge $800 a day for a bush carpenter, I told him I would accept a days pay for a week and his response was when are you coming back an for how long.
Regards
Brian