they'll do the job just fine. Yes they give off H2O vapor so they're not good full-time winter heaters, but they don't really throw off so much that I'd rule them out for occasional use. I use a Coleman catalytic (I think it's called "Black Cat") that uses a one-pound LP canister and it takes the chill off while breakfast is cooking. We don't run it while asleep or in a sealed cabin. Blankets and sweats work just fine while asleep without heat.

I use the same canisters for the rail-mounted grill and they're readily available in marinas and convenience stores. I have a special vented locker for LP with extra room to store these but in the past I've made a storage housing out of schedule 40 PVC pipe like you can buy cheap in Home Depot or hardware store... A few end caps (drill the bottom one with a 1/8" vent hole) and a 1/4" wide strip of aluminum bent inward at 90-degrees at both ends to lift out the stacked cans. A few band clamps or tie wraps to attach it to a stanchion.

I think a generator is a lot of baggage (and noise) just to supply occasional heat. If you have other justifications and will have the generator aboard anyway, then the Honda or Yamaha 2000 will do the job.