I-400 pending, Green Cards expire in December. Should we apply for GC renewals for travel?

[Emdee406 0]

First time posting here...We just had our Biometric screening and fingerprints done. Currently our Green cards expire in December, and we have been told that the wait time for naturalization in Utah has now stretched from 6 months to 1 year, due to a massive increase in applications. We both have older relatives back in the UK, and are worried that once we hit December, that we won't be able to visit them if an emergency occurs, without paying $580 x 2 for new Green Cards.
With large medical bills pending, we don't want to pay out $1160, on top of the I-400 fees!
I know that we can't apply for GC renewal BEFORE 6 months, and I've read snippets about an I-551 stamp, but it's not very clear, and the USCIS site is not very helpful in this regard.
Can you get an I-551 stamp giving us an extra year WITHOUT paying for GC card renewal? 

Has anyone else been in a similar situation?

Thanks!

[Starkilla09 366]

Unfortunately you’ll have to pay to renew your green card, take confirmation receipt of your I-90 fee payment to your infopass appointment to request the stamp. The only situation you could’ve been able to get the stamp for free is if you had a pending I-751 petition to remove conditions with an expired 2 year green card and extension letter expired as well. Sucks but you guys are gonna have to do this unfortunately and also pay N-400 fees if you want to naturalize. If money is tight you can prioritize and have N-400 done, cancel your trips and do it later once you naturalize. 

[AK_2014 113]

Is this similar to your case? (When you say I-400, do you mean N-400, which is the citizenship application form?)