I've had the idea to create such an opportunity, but need some start-up funds to prove its viability. Specifically to create a suitable row-boat and travel the length of the river. I am an keen amateur boat builder, if the trip is as successful as I think it will be, I'll then build more such boats so I can guide others down the river too.
So this first trip is going to be for research purposes, to try out the boat design that I have in mind and see how long it will take to do the trip, and so on.
So far I've not heard of anyone doing this particular trip down the Derwent River by rowing, though its done frequently by kayakers. In my opinion, rowing is going to be better than paddling a kayak as the river has many flat water sections, including some long lakes behind hydro dams, and rowing is easier than paddling on flat water.
I have been keen on recreational rowing for a few years, people have been building some very nice rowing skiffs for this purpose and doing some interesting trips, including myself. For this trip though I want to design and build a different kind of boat, a very simple design for low-cost construction, and very robust to handle the bumps and scrapes that are inevitable in a river.
I want to start the journey as far upstream as I can. This is at Lake St Clair (see the image below). I'll then follow the river all the way down to Hobart. I cannot do the whole river length as its been diverted (for hydro electricity production) in an upper section.

This will make it an interesting adventure that I can document and publish an account of, I'll probably also keep going once I reach Hobart and go as far south as I can get, to Recherche Bay. This longer journey could take up to 8 days in total. If I go ahead and organise to take others down later on, I'll most probably not start the trip at Lake St Clair, due to the diversion mentioned, but lower down and finish the journey either in New Norfolk or in Hobart.
At the moment I have no regular work, so this idea is an attempt to try something new. As my cash reserves are non-existent I'm hoping that I can get sufficient funding via Pozible to get this business idea 'off-the-ground', or should that be 'on-the-water'. Now I am looking for seed funding to show it's a viable proposition, I am seeking your kind support to do this. I intend that my early Pozible supporters will have priority for booking trips if and when I can bring the guided trip idea to fruition.

I really love the Tassie outdoors and creating an environmentally sensitive tourism venture that gives people a different but very safe and relatively undemanding outdoor experience is what I am seeking to do here. Not everyone can or wants to carry a heavy pack into the wilderness. Travelling by water, and in this case down a scenic river, provides this opportunity - as the famous quote goes: "Believe me, my young friend, there is nothing—absolute nothing—half so much worth doing as simply messing about in boats."

Although me doing this first trip is for a specific reason, to test the guided trips idea out, the rewards that I am offering relate to the boat that I will design and build. If I make the decision to go ahead with the guided trips then I'll probably make that a separate Pozible project. So at this point what I am seeking in money is a relatively modest $1500, I do want to see this happen and your assitance will make it happen much sooner.
The row-boat will be suitable for recreational rowing on flat and open-water, be stable and light enough for one person to lift on and off a roof-rack (a bit heavier than a 5m plastic sea-kayak I envisage) and capable of taking a passenger. I'll make the plans of the boat available to my Pozible sponsors for free along with good building instructions. Construction will be done by the easy stitch-and-glue method and incorporate built-in foam bouyancy for safety.
How The Funds Will Be Used
To buy the boat and rowing equipment new would likely to be over $4500 and then not be ideally suitable for this kind of trip. I can probably halve that cost based on my past experience.
The Challenges
A good idea!
This reward is simply the "great idea do it" option, all I can offer is my warmest thanks via email and the opportunity to join a mailing list to be kept informed of progress, with pictures.
Float my boat
My row boat plans will be available once the boat is developed and tested, if you want a free copy, or just to help me more generously with the project, here is your chance. The design will be suitable for a single person, with sliding seat if desired, and a passenger too. The concept is for simplicity, light-weight, toughness and stability. Also, after the trip I will send you a thank you note with a copy of one the best photos I have taken, kind of a thank-you post-card.
Push it along
This is basically the same as the 'Float my boat' reward, but if you are really keen on doing the guided trip, or a similar one yourself sometime, and want to give the project an extra push along, here is your chance. For this reward I'll keep you well informed of progress and if you are in Hobart, meet with you for a chat in person if you so wish.