Didn't have to go through with the train plan afterall.....

Something I realized recently....The whole reason why they needed the train in the first place was because they were in a race against time so to speak before Buford shoots Doc. Their whole plan for getting home had to be accelerated. If it wasn't for Buford, surely Doc would've been able to take a month to rebuild the fuel injection manifold, get his hands on some crude oil and create gas. It most definitely would be a lot safer and a lot less riskier than sending it over a ravine.
SO..... After Marty defeats Buford, they see that both of their futures are no longer in danger on the tombstone. Why would they still be in a hurry to go through with it? The plan from there should be abort the mission, get the Delorean back to the shop, rebuild fuel injection manifold, distill some crude oil into gas and safely run the Delorean to 88.