Span width increases Const costs proportionally more than length, especially if you want clear span.
What else are you going to do with the shop? Doesn’t sound like you’re a gearhead or cabinet builder, however I’d still build as big as you can fit/afford.
Resale wise, no one ever looked at buying a house with a detached shop and said “oh no, that shops too large, let’s look for one that is more cramped. “
However what your proposing at 60’ + wide is more like an airplane hanger than a RV barn. 40’ wide will get you 3 bays and room around each vehicle.