LVM here too, cheaper options but it is fast and rebuild-able if any part of it breaks you can repair it which I like versus the cheap stuff. I’ve seen cheaper versions of same thing out there if you search though. Downside is they are freakin loud! Literally only takes a couple minutes to do a 14’ boat though.
As far as extension cord, just go to BatteriesPlus or whatever you have and get a battery. 7 to 12 amp 12v batteries are light and small and rechargeable. Portable power and you can go several inflate/deflate cycles before needing to recharge.