Your numbers don't work.
Because you can buy a Clio for a few hundred quid, and prep it for 2k your idea of making the money back over 3 weekends (£666 profit per weekend) by it's very nature means your "customer" only has to do 3/4 races and they'd financially already be better off buying/building their own car. Hence arrive&drive makes more commercial sense for a provider/customer when running costs are sensible but purchase price is high (caterhams, formula ford 1600, britcar).
As soon as you mention "arrive&drive" you need to offer benefits to justify the profit: lending HANS device, set of wets & spares mounted, someone to run the car, consumables/fuel/tyres/entry/insurance/transport all included in the price, money-back-guarantee for mechanical failures... Obviously this is fine if you've already invested in all of this equipment.
For a Clio the ktec series seems the best shout for a successful arrive&drive by a long shot? It actually has some form of TV coverage & PR (bragging rights for the customer), big equal grids (guaranteed competition against loads of cars regardless of talent not just the 2 or 3 of a similar spec), you don't don't have to spend spend spend to keep the car on competitive laptimes, well supported, minimal running costs, higher build cost so more financial sense for a customer...
Thanks Steve for your thoughts ...
I didn't offer up any numbers nor the package, it's not entirely critical in my opinion and any moderate risk can be covered.
My experience at novice level is that there is general requirement for a service for an arrive and drive without all that you list ... Certainly you'd never offer up a HANS device nor anything else driver related, it's just not done, drives are cars and perhaps a package that is as you say spares etc but still that's limited to what's reasonable and never any less than I carry in the van on race day anyhow...
As for cost well, yes it can be £600 for a rental ... £1k including fees, that's my point really with regards to cost ... All components generally are straight swap into another clio in the event of that much of a on track moment so you don't "lose" a car more like a shell / front end at worse case... You can insure that risk, or more importantly the driver can or choose to pay to replace it as required.
When you say profit ... In honestly I wasn't thinking making money more over just having a car pay for itself, & technically contribute towards my race running costs, any profit would come at the sale point of the car whether it be race car, Parts or scrap.
Also, don't forget drivers arnt as perhaps happy to tinker or have access to guys that do like you or I Steve when building a race car hence why arrive and drive exists ... Ok more likely in higher echelons of motor sport agreed but I've seen Paul Hollywood racing in an Alfa to get signatures for GT racing this year, finish the race to obtain a signature at under £1k is good value for him, likewise most drivers wanting to turn up to race on track to see if it's for them again is good value otherwise its £3k cheapest for for the same thing and then the hassle to buy it, get it there etc ... And of course sell it if it wasnt for them.