No way to effectively patch a sidewall ... especially on the side of the road. It will never hold. Even a big hole can be hard to put a plug in or patch.

A tire shop MIGHT be able to fix the tire ... but when traveling ... a tube in the tire is your best option. Its what we do. It works.

Be SURE to check and clean inside tire for sharp debris before installing your new tube. Often times bits of nail, screws or staples are hiding in the tire. You won't see it ... but can FEEL it with your hand. (Use caution)

I would go over your owners manual to learn how to remove plugs and air filter and such.

Go to owners forums to get other experiences on drowned out GS's and how the owners handle it. Many do the WRONG THING ... and RUIN their engine ...
HydroLoc is always a danger if engine fills up with water ... and then crank it over. (It will bend a rod ... RUINED!)

Guys also ride with too much water in the oil .... and never even know it ...
once again ... RUINED ENGINE.

If crossing really deep water, have friends standing by to help or let a more experienced rider take the bike across the water. I rode a friends R1200GS out of a very tough area in Mexico's Copper Canyon. He had fallen 5 times ... and finally was exhausted. He rode my Vstrom out ... which he found much easier.

Practice at home taking things apart, doing basic services: Oil and filter change, Air filter change, Spark Plug change. Practice also removing wheels from bike, learn where all the spacers and bits and pieces go.