If you keep your MEIR current on an aircraft its not hard to keep your SEP current also, since the MEIR renewal counts as 'Renewal by Test' for your SEP rating (yes even though it's not done in an MEP type).
So it means your annual MEP / MEIR renewal is also an SEP renewal, keeping the whole single pilot bit of your licence up to date (unless you fly a PA46 or other v. complex type of course).