240V Extension cord question for the gurus

I know there is quite a bit of info regarding this topic that has already been discussed. However, after searching I still have a few unanswered questions.

I am looking to build an extension cord to run from a 30amp 3 prong dryer outlet to a 5500w boil kettle. My question is in regards to wire size. Due to being a renter, I am unable to add a closer outlet and am faced with a distance of 60 feet to the outlet. I am aware that NEC code says 10 gauge wire is sufficient for the 30amp circuit. I also realize that at 60 feet there will be a descent voltage drop. If I understand correctly the NEC does not care anything about voltage drop only carrying capacity. If I use 10 gauge as opposed to 8 gauge is the voltage drop my only concern. I can live with some power loss at the element as 5500w is large enough lo lose a bit and still provide plenty for a vigorous boil.

Most importantly I want to do this safely but if possible stick with 10 gauge soow wire as the 8 gauge soow is about twice the price per foot. If I am correct the only downfall with the 10 gauge is the loss in voltage not a safety issue. If this is incorrect logic please correct me.
Thanks,
Jim

I don't have any trouble running a similar setup

I run pretty much the exact same setup, except my cable run is a tad shorter. I register the same voltage at the end of the cable as I do at the outlet.

I feel you though, that 10/4 cable is freakin expensive for the plyable extension cable type.

10 awg will carry 30A fine. But not 50A. And don't use romex! (looks like you know that...just sayin')....