it will eventually show up on your metrics and look scary though if this is a one time issue and you are not a new seller so most likely it is not going to be an issue (fingers crossed).
yes probably good to sell stuff quick. go ahead and test toyplanet's repricer limits on something you have a ton of they are blocking you on and watch your sales fly. it will feel good and metrics will improve.
this is america and you can choose to ship and sell how you want to.
personally, i would never ever drop off at USPS partner. there is zero accountability - especially for a set that large and its not going anywhere over a weekend. would be better to hold onto it and drop it off first thing monday morning.
second turn off PO box - i like to have options in choosing shipping. USPS PRIORITY is never ever the cheapest option for shipping a large set unless its around the corner. unless you are super desperate to unload everything fast, you're not missing out on many (any) highly profitable sales.
finally, here's the settings to ensure you never torch your margins FBM something over 15oz to Alaska, Hawaii, or Puerto Rico ever again.