Not sure why you are only focused on the guard. There is a reserve base an hour north of you that flies as well. Two flying reserve units, and a guard unit that flies UAVs... Plenty of pilots that fly for CBP also fly out of March ARB.

Secondly, time is of the essence for you. You need to be in UPT by your 30th bday, otherwise you need an age waiver, and those are hard to come by....

Also, consider the guard/reserve like a good 'ole boys club, so networking and face time are important.

Lastly, not having any flying experience or ratings is not gonna work in your favor. That doesn't mean it isn't possible, but your competition will generally have a commercial, if not be a CFI, with a fair amount of flying experience in general aviation. These units that are gonna spend millions of dollars to send you to training, like knowing that you'll be able to get through the training and when you have no prior experience flying, that leaves them guessing.