If you are truly at the max GVWR for your vehicle but are still under the RAWR and you add 100lbs ever now and then I wouldn't be that worried about it. If you are already well over then it could become a problem. How much leeway do you have now with the GVWR and the RAWR? You can adjust some how the trailer is loaded to maybe help with the tongue weight but I doubt it will matter much unless you are loading lots of heavy items up front. You will get it figured out. Its a learning process and I'm glad you are at least asking questions. Some people just assume its fine.