Looking at the above graph, the last leg of the trip Amboy to Ludlow is only 28 miles, but it's all uphill so starting in Amboy with RR=53 was cutting it close, especially as that great RR was the result of the long downhill run (what did your fuel gauge say?). Knowing that ahead of time I would have kept her around 25-30 mph.
Looking ahead to Barstow, the campgrounds don't look too promising, but I see three welding shops - hope you brought some adapters, as they should all have 240vac.
EVs: 2 Wht/Blu SE Prem., '13 Tesla S85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV