I run a mailorder that sells records, cds & tapes. The latter two are easy to ship, but records are obviously more difficult, due to their size & fragility. Historically, I've only offered one packaging option for the records, and added the weight of said packaging to each item as I add them to the website. However, I'd like to start offering two different packaging options for vinyl lps: the standard mailer and a much-sturdier upgraded mailer. The standard ones are already built in to the weights & rates, but these new mailers will need to add an additional 10oz to the weight AND $1 to the handling fee. How can I do this on the Basic Shopify plan? Thanks!