If you don't add barley you should definitely add some rice hulls to help with lautering, since a 100% wheat mash will be very sticky and will easily give you a stuck mash. Normally 1/2lb is plenty, but with a 100% wheat, you probably will want to push this to 1.5lbs of rice hulls - but this really depends upon your equipment. (E.g. for BIAB rice hulls are not needed at all.)
Also, you should add a protein rest at 122F to the mash to help reduce haziness - 45min to an hour. This also reduces gumminess and helps with lautering.
Also, think about how dry you want to be. I imagine it will be very dry given given you have 38% rice extract. With the recipe as is, the main control over body is with mash temperature. To avoid a beer that's too watery, you may want to add some carapils, or crystal wheat (if you want to stay 100% wheat) to ensure there is still a little residual sweetness and include a rest the high side - e.g. 160F, to help promote dextrins.
Even after a protein rest, the beer will be naturally hazy from the high protein content in wheat. If that's an issue, you'll want to add plenty of kettle finings, such as irish moss/whirlfloc, and consider using finings in secondary after the lager period too, to help clear the beer further.