I am not sure what you mean by "pays for any machine or vehicle rental and exceeds 30 days, there are some limitations or restrictions".
Each of the items that you have mentioned, rental fee, repairs, gas, and toll charges, are deductible tot he extent that they are business related.
If he doesn't have evidence because he paid cash, that is a problem of its own. He should have kept, and in the future should keep, a log book where those items are written down when they are paid. As far as the rental fee is concerned, he should be able to get documentation from the provider of that amount. As for the other items, he should make realistic estimates and understand that if the IRS questions any of it, the burden of proof will be on him to prove that he is entitled to the deductions.
In the future, besides the log book, he should get an expanding file and keep receipts for gas, repairs, etc. in that throughout the year. Records for toll charges should be satisfied by the log book.
He should keep in mind that the expenses should be in line with the income reported. For example, if he reports $25,000 of gross income and $10,000 of toll charges, that does not reflect reality and would likely cause his return to be questioned.[email protected]