If you see my post 'Windmills and Wine' on 'Voyagers and boaters on the Go' you will see that I've just done something very similar (for the second time) and maybe we could be of mutual help.
When I saw your post I checked out long term hire rates and it's very very expensive especially as you wish to go from one country to another as basically there's nothing to stop you from selling the boat and skipping with the money and hire rates are prohibitive for that very reason.
For example just the month of August would cost you 3,000 per week.
I rang a couple of company's just to check it out and only one would consider such a deal and they wanted 60k including deposit and insurance, plus they would charge for engine hours run on the boats return.
Would you consider buying a well proven boat with a safe cruising record ?
For 2 reasons, 1, it would be difficult see what you indicate in 6 months. 2, you'll have an asset to sell after your cruise.
I've a Birchwood 33 ft. centre cockpit motor cruiser for sale that's suitable for either coastal, river or canal cruising.
The layout is open plan with a forward V converting to a double with an infill, dinette, galley with s/steel 2 ring cooker with fiddle rails, grill,regulated oven. 12/240 volt new fridge, shower compartment with w/h basin, electric toilet. Cockpit with lockable side doors for security seating and folding table for al fresco meals.
Rear cabin with double bed wardrobe, en suite w/h basin,manual toilet and wardrobe.
A mains hook up with RCB, 240 w of Solar Panels for independent cruising.
The dinghy shown in the photo's is not included in the sale.
An 9.9 hp outboard is included if you wish to buy a dinghy.
She's powered by a single 80 hp Perkins that's been regularly serviced
If it's of any interest the price is 47,000 Euro and she's lying in Narbonne in the South of France beside the canal Du Midi will be sold on a first to buy basis.
Please let me know if you have any interest in it.