276 Hi Mason. An obvious but friendly reminder to be mindful that even though you will be training your dogs to stay within a set perimeter this is not security for anything else that could potentially enter that perimeter. Just something I wanted you to remember to be mindful of.
In addition to the remote training, you can always look into some type of free standing outdoor enclosure. Some of them are much like gazebos. This could come in handy in case you ever need to temporarily secure one or both of the dogs for any particular purpose while outside. They do sell outdoor animal enclosures with a top cover to protect from the elements. I myself have one that can be adjusted in size by adding or taking away panels. Although it does have a cover for outdoor purposes, I have removed it and I use it indoors as a roomier alternative to a crate for my dog.
Remember not to rush the training process and good luck!