I can understand you positions and thoughts - and I agree.
Alos having had the opportunity to work these events I can also put a differnt view forward:
Most poeple that attempt these events are, in all honestly, not ready to do them - be it physically or mentally. The suport and administation that accompanies these events means that large discounts can be had, for large bookings -
Ferry prices are not passenger prices, but reduced bulk price. I'd be surprised if they give you anything off, even if you say you are doing it for charity.
Support vehicles - professionals can be there at all times for mechanical or injury problems. What is your back up if you come off due to a blow out, farless fixing it or getting to somewhere.
Escort group - busy roads (or even back roads can be more dangers as syslists are unexpected) in a group, with a support vehicle, lights flashing and either holding vehcles back / arranging when to pass etc. Assume the ndividual has lots of H-Vis and is aware that european drivers are VERY different to UK drivers.
Food and water - you can only carry so much - set up points where people can ridethought or stop for some food / gels / refill bottles. Whats your plan - subsist off energy bars and carry 20 odd full bottles, or buy as you go?
Reputation - (nothing personal) someone says to be that a friend of theirs is doing form A to B., self supported. How do I knoe that they arent taking anythoung out for themselves even to cover base costs at cost price? Some are honest and upfront, some will take the hit, some may take base cost plus a mark up, who know. This is a published X -Y=Z
See those chuggers out on the street - the compaies they work for charge the charity £20 - £90 per person they sign up. So you £5 a month can take between 4 and 18months to pay off the person who signed you up, before y actually "give" to the charity.
There is a hell of a lot that this goes to pay for - and running costs of the charity also add up.
Charity is anything but free.
And FYI the mechanics for a L2P get between £200 and £400 depending on the event organisers. Flat fee, no mileage, additional fuel or sustenance claims, for what is 4 days work. Leave saturday 0700Hrs from London (so probs up around 0500), they have 24Hrs to get to Paris, Ferry sometime Saturday morning, there by 0700Hrs Sunday morning, and ferry back 1100rs local Monday (sunday to sleep as you've been up for 24 / 36Hrs getting / driving there). What is included is ferry crossing ticket, and a share of a double / twin / family room with other support staff / riders (they notmally book out a complete hotel for the day / night).
300 odd miles each way = 600 return, at 400 miles per tank of fuel, £95 a tank takes tank and a half so that's £140ish aready gone, buy own food and drink (reserved for riders only!) so say you could do that for £50 for 3 days, so where's the profit .....?
Charity eh?