I used to think that. Then I started using a very light one on my Southern Tier trip with a few pounds of stuff in it for that day here or there where I needed to carry extra food and water for long sections without services. I found that I didn't mind it at all and started using one all the time on that trip to carry the stuff I didn't want to leave on the bike. It was nice that my wallet, phone, and other theft worthy stuff just stayed with me automatically when I got off the bike. It was also nice to have the things I might need during the day there too. I didn't find it uncomfortable at all. It was comfortable enough that I kept using it even after I didn't need to.

I liked the setup well enough that I used it on the tour after that as one of three primary gear locations. I carried the gear split as follows:

• 2 lb 7 oz in bag bag
• 3 lb 5 oz in backpack
• 5 lb 7 oz in a dry bag strapped to the top of a little the rear rack

That was for an ultralight camping and cooking trip for my primary gear, but I see no reason why it wouldn't work for the OP to carry some extra stuff for a few days especially since he says they will be low mileage.

On another note mailing things home, having things sent from home general delivery, and buying stuff on the trip when the mode of the trip changed have all worked well for me. For example when I found myself at the end of a long tour and staying with family for a week long visit and only bike clothes in my possession I just bought some new clothes.