I recently had a lot of redo on the caulking on the sidewalls of my MH. The job the dealer did to fix the non-UV caulking Newmar put on in the first place is coming undone, peeling, cracking, etc.
I started to replace it and found I could not use the hand caulking guns and it just hurt too much afterwards.
I found an air powered caulking gun at Harbor Freight for less than $15 that works great and by adjusting the airpressure to match the viscosity of the caulk and how fast you want to work, I can lay a bead and almost not need to smooth it out. I did one track on the lower side of the MH, one side in about 10 to 15 minutes after it was cleaned out.
If and when you have to caulk again, I suggest you consider the air gun. Be sure to get one that fits the cartridges you will be using as there are 2 sizes.
Also another hint. Push the gun as you lay the caulking rather than pulling. You can see better what you are doing and you will have better control of the bead you are putting down. I learned this from a glass installer and believe me, it really does work.