JT37, welcome to the site. I read your bio. Pretty cool that you have kids who love the game so much. There is no doubt that it will be fun for them to hit a few out on the short field. However, you may want to consider a few things...
If they love the game as much as you say, they undoubtedly want to play at the next level and the next, etc. They would benefit far more, in that regard, from playing on the big field this coming spring instead of wasting a year playing against competition that can't even touch their pitching. If they are as good as it sounds, it probably wouldn't be to difficult to get the next league up (pony or whatever 13 ad up league is in your area) to allow them to play.
It really won't be all that much fun for them if the team is going to be as dominant as you indicate... not for them and certainly not for the other teams. If they have to play on the small field again, it may make sense to offer to "split up the dynasty" and spread these kids around so there will at least be competition among the teams. Then the boys can play together in all-stars and go up against the leagues with more kids to draw from.
I know these thoughts are not going to be well received when you first read them. Try to think two years down the road... four years... Also, try to think ahead as to how the 12 majors season will play out for everyone in the league. Yup, dominating in a league where maybe you and the boys have taken some lumps in years past probably has quite a bit of appeal at first glance. What would really be impressive, though, is if you could look beyond and see the big picture.
In any case, congrats on being able to enjoy kids who love playing!