At some point in the election, based on some criteria I do not understand, a Presidential candidate crosses some threshold of seriousness and they are given Secret Service protection.
I have a similar idea. At some point in the election, candidates should have the ability to have a certain number of their proposals (spending, regulatory, tax plans) scored by the CBO, just as legislation is scored. Use of such services would not be mandatory, but I would assume that there would be a certain pressure to get one's own plan scored if one's opponent is waving around a scored plan.
CBO scoring has all sorts of problems, not least of which is the common trick of spending like crazy for 9 years and then inserting some huge imaginary savings in year 10 that makes the whole thing score as budget neutral. But folks will be able to see that (if they want to) and I think the advantage of being able to see actual costs and revenues of candidate plans in the same way they would be viewed as legislation (which presumably is the goal of candidate proposals, to turn them into real legislation) would outweigh these shortcomings.