Well, for "fooling around at the trap range" it is ok, but for any ATA or other competition that goes by ATA rules you can't.
ATA rules set a max velocity and game loads are usually over it.
Also, you mention 7 1/2 shot which is good but other game loads (6, 5, 4, etc) cannot be used as most trap ranges have a sign up specifying 7 1/2 shot or smaller.
Using 1 oz loads also handicaps you a bit since you have 1/8 oz less shot than a normal trap load, but it's not that big a deal.
And other than you are beating yourself up with more recoil than necessary, it shouldn't be a problem to use them in a non-competitive manner