You will never get a HMMWV back into the country even from Mexico....If some of you remember some time ago of a GI or contractor stationed in Saudi Arabia
took an M1026 and turned it into an H1, Beutiful truck when all was said and done, he tried to ship it back.....it stayed in customs hold in US for years!
Not sure what eventually happend to it, I know he tried to sell it on E-Bay, sold as is and where is....LOL
He had a bunch of money invested in that truck.....You cannot re-import current "M" series vehicles back into the US, They can leave, but they can't come back.
Alot of the reasons have already been discussed. Also as stated, why Bother, there are plenty of HMMWV's for sale in the US.