Around here the only places to charge our Tesla is at camp sites. I have a buddy that tows an rPod with a model X. When he gets to a camp site plugs the camper into 30a and the Tesla into 50aand charge while flat towing or charge at campsites in the 40 and 50 amp outlets
The alternator only produces energy as needed. They're all variable output. Every kwh generated by the alternator comes from diesel fuel being burned in the engine. So you're 40% efficient to the alternator, then probably 70% efficient from there. It's likely in the ball park of getting 10mpg or less direct burn diesel.The alternator is producing electricity anyway so might as well harness that energy
I like the idea. But the Tesla semi can't tow a full trailer yet and make it between charging stations. So it's still a long way off before it's actually ready to be converted to an RV. It's not really a functional semi in a meaningful sense other than that it tows an empty cargo trailer around.