Even though the Tesla MC240 says "30 amp capable" right on the front, I don't think it is compatible with the RV TT-30 socket. An adapter cable such as this:
only provides 120V, and the MC240 expects 240V.
I think the 'proper' way to hook to a TT-30 would be using the Tesla MC120 with a TT-30 to NEMA5-15 adapter like this:
Unfortunately the MC120 is designed for lower current applications, typically drawing only 12amps. What would be nice is yet another charge cable that had a TT-30 end, 30amp GFCI, and the pilot signal electronics to tell the Roadster that it can draw 24 amps @ 120V from the circuit.
The 50 amp RV socket (AKA "NEMA 14-50 Range socket") is used a little differently in RV campgrounds than it is in home use. Rather than powering a 240V device directly (such as electric range or welder), the RV typically splits the two "legs" of the 240V into two 120V circuits. One powers all the 120V outlets (e.g., TV, Microwave, lights) and the other is used solely for the air conditioner. Because some RV/campsites only have the 20amp 120V outlet + 30 AMP 120V outlet, and many RVs want the NEMA14-50 socket, some have created so called 'cheater cables' that let you take the two campground 120V outlets, pass them through the NEMA14-50 then split them right back to two 120V paths in the RV. Even though the NEMA14-50 socket & plug were used, no 240V devices would be drawing from both legs. Those wanting to charge a Tesla from a NEMA14-50 should be weary of these 'cheater cables', particularly with the "Roadster Foundry" kit. The circuit breakers behind the cheater cable probably don't have the right amp ratings to support full 40 or 50 amp charging. If you plugged both legs into TT-30s at separate camp sites you might get 240V@30amps (if the two TT-30s are different phase) which might work with the MC240, but if you use the NEMA5-15 adapter and have one leg hanging off of a 20 amp breaker, the max charge current could be very limited. (Is it possible to tell the VDS to draw 240V@16amps in this case?)
By the way, much of what can be said for campground hook ups is also true for "shore power" at boat docks.