You don't need to really figure out how to do the hex encoding... just create an "unsigned" transaction using coinb.in (https://coinb.in/#newTransaction)... You can even use a downloaded offline copy of Coinb.in if you're super paranoid. After you have copy/pasted in the addresses containing the inputs you want to spend (PROTIP: use the "Coins" tab in Electrum to see where your UTXOs are)... then click the "Advanced Options" and you have the ability to specify the nLockTime, RBF etc... then load the generated hex into Electrum, verify it, sign it and broadcast it... easy 
The only catch that I can see, is that you need to manually calculate and specify the "change" address and payout... but that's not exactly difficult
The only catch that I can see, is that you need to manually calculate and specify the "change" address and payout... but that's not exactly difficult
i appreciate this, thanks.... i'll look into getting an offline copy of Coinb.in to try this myself later, as i was also unable to figure out how to use the locktime feature in electrum from the documentation.
i hate to ask, but when you say "manually calculate" the change address and payout, what do you mean exactly? you just mean we need to manually do the arithmetic (inputs - output - fees = change), right? i guess if we're wrong, the transaction would return invalid anyway...