Can head gasket be down with engine in the bike and are there specialty tools needed?

I will hopefully my brother in law will be able to come over within the next couple days
There are a myriad of ways to check the oil seals without tearing it down, but what I'd do if I didn't own the tools I do is:
Do an oil change with inexpensive Castrol oil. Then I'd use the tester linked below, if the tester shows blue aka no exhaust in coolant.
Ride it, daily, for at least 30 minutes preferably on the freeway, checking oil before/after each ride to verify the condition.
If at any point after a ride it shows milking, I'd go ahead with HG replacement. You may only see milking before a ride, that's actually fine see below. It's not a motorcycle only problem, my wife's opel corsa had the same issue, she only drove it in town while living in Germany and it would condense a lot of water overnight.

the tool:

here's a guide:

and a video:

if milking is only before a ride and tester stays blue, you have a condensation issue in your environment. It's fine, just ensure when you do start the bike, you like it run long enough to burn off contaminants and don't do short 10 minute or less starts/rides exclusively.