There are lots of YT videos on this and they should be easy to find. I've done this job every spring for the 10 years I've owned my 23' trailer. should take less than an hour on a small to med size RV unless there are extensive areas that have cracks in the existing caulking. If you buy the right caulking product, some solvent and a caulking gun that's all you need. Dicor seems to be the industry leader, and isn't expensive. My small town walmart and amazon have it. One tube ($12-15?) should be all you need.
The good news is that the job of putting new sealant on the cracks doesn't require much skill, unlike the caulking in your house which take skill and experience to get a professional looking result. The original factory caulk isn't applied in a fancy finished manner. It's put on thick to fully seal the joints/seams where the roof material is joined or where the are "penetrations" in the roof material for the AC, antenna, skylights, etc. IMO, you actually want the annual caulking job to be visible; that way a potential buyer will see proof that you've done this important job regularly. The newer caulk will be obvious once you are up on the roof.
Also good news, unless you have an older, neglected RV, you shouldn't have to remove any original caulking. Just add new caulk to the places that have cracked due to age and weather exposure. If you store your RV under a shed or use a cover the need for recaulking should be less. If your RV sits outside year round it will take more time to hit all the cracks.
Roof caulking is the area you should be most diligent about, but you should also check the caulking on all the vertical seams/penetrations for caulk failure or age/weather related cracks. The videos suggest you do this job annually, although checking for cracks that might need attention more frequently is probably a good Idea. If you need to caulk vertical seams you will need to buy the type of caulk that isn't "self-leveling" so it will stay in place once you apply it. Use self-leveling for the roof caulking; you want it to spread a little to better the seal the cracks you are trying to fill.
As you probably know, intrusion of water from leaky caulking on the roof and/or sides is one of the worst things that can happen to an RV. It's an easy problem to prevent, but a very expensive one to repair.
Good luck with what should be a pretty simple job!
