Steve
Head turner is flying VFR so TOPO is not necessary as he should be looking for rising terrain with the old mk1 and flight planning.
Not sure what a 530 is (is it a Bendix King KMD system?) but have you not got a display that will pop-up for any TA's or RA's??
Most GPS systems will also alert you to any airspace ahead that is about to be entered without the need for it to be constantly displayed.
To me, 4 GPS is way over the top. 2 max