You're right about losing the oil pressure light unless you get an adaptor.

The problem you will have on a 4x4 is that space is very tight - most adaptors will foul the oil filter, although I think Mike R has a new adaptor that gets round this...

The alternative is to fit a sandwich plate - a plate that goes between the filter elbow and the filter itself with take-offs for the senders. You could then fit a temperature gauge if you liked. Raid HP do them for reasonable cash - I bought one but have never fitted it. If they don't have stock I could be tempted to part with it

Removing the starter motor makes access to that area MUCH easier

Neil.