Yes it can be done but it is a little more work.

Pull the cluster, lower or remove the steering column and the two kick panels. Peel back the carpet around the high beam switch in the floor and it is usually easier if you remove the glove box on many cars.

That should give you access to all the wiring connectors. Just peel and replace.

I am not a fan of Voltmeters. A voltmeter is rarely accurate enough to let you know there is a problem until the problem is progressed enough the car may not start or run. An ammeter is an immediate indication of a problem.

More importantly an voltmeter will not eliminate the shortcomings of the harness just the ammeter insulators that are the most common problem. You still need to address the weak connections at the bulkhead and ignition switch.

I still suggest you take the old one out and give it a shot at rewiring yourself. Even if you replace it it is a good skill to know.