We ask our plot holders to put name/plot number on their bank payments.
A potential problem with this is ever changing personal details, specifically email address which is what the OP mentions. If using a CRM to manage membership and to send invoices out payment reference should be the invoice number allowing for very quick reconciliation as you suggest. If there's no unique invoice to pay, tracking down plot number against an email address (I'm guessing paypal is also involved here) could be problematic especially if the a plot holders email has changed, is spelt wrongly, doesn't fit in the reference box or if the payment method isn't tied to the email recorded on the plot contact.
All manageable problems for a small number of members, but not a robust system design or scaleable to any degree. Back in my previous life, period based recurring payment processing (like membership,rental and storage) was one of the most common applications and middleware projects I would get asked to write.