Is there any way to pull these fields into a Saved Search, I am not finding them in the list of fields?

the classic issues with a/r and saved search. i do not believe this has ever been resolved but i will leave it to the community to answer.

I just looked at the Aging Report saved search Finance uses. The aging buckets are calculated with formulas - they customized it from a delivered saved search. Here's the formula for the 1-30 day bucket:

CASE WHEN ({recordtype} <> 'invoice' AND {recordtype} <> 'customerpayment' AND TRUNC({today})-{trandate} BETWEEN 1 AND 30) THEN {amount} WHEN ({recordtype} = 'invoice' AND {duedate} IS NOT NULL AND TRUNC({today})-{duedate} BETWEEN 1 AND 30) THEN {amountremaining} WHEN ({recordtype} = 'invoice' AND {duedate} IS NULL AND TRUNC({today})-{trandate}BETWEEN 1 AND 30) THEN {amountremaining} WHEN ({recordtype} = 'customerpayment' AND {duedate} IS NULL AND TRUNC({today})-{trandate} BETWEEN 1 AND 30) THEN -({amountremaining}) END

It's a summary saved search.

This would be great if my search was on Transactions, but my search is a Customer Record saved search. Might be able to make it work using related records?

I'm not sure. If you can get a saved search from your custom record with a due date and amount remaining, I would think you could use formulas for the aging buckets. Someone more knowledgeable than I am can probably give you a better answer. 🙂