FCL.725 (c) states take the test within 6 months of starting the course. Under normal circumstances we train MEC and MEIR almost immediately after one and other (on separate training course manuals) and argue that training for the ME/IR especially as OEI approaches are being covered counts as 'continuation' training once the 6 month window for the MEC has elapsed. Never had one thrown back (yet!). Mostly not the CAA but we have had a couple through the CAA go uncommented on. Exam is 'two' flights but one test event for the MEC and ME-IR-SP(A).
Silly rule.
As stated, if you don't need the MEP rating then just revalidate the IR (CAN'T RENEW) in the sim. If you have to renew, then you may as well renew the MEP as well. Typically, when I am assessing someone for 'training as required' for renewal, IR is 'trained' in the Sim and x flights in the aircraft to cover MEP (with appropriate OEI approaches). Again - not had any comeback (yet!)
HTH
DD