Yes, you could experiment with water surrounding the glans in the chamber as a means for direct pull. However, this will not prevent the tendency for cavitation to occur under traction in which separation of the glans from the chamber wall forms an air pocket within the liquid. In any case, separation from wall is the leading cause of blisters formation.
However, Stealth has developed the principal of Glans-Lock™ into a science. When this principal is properly applied the bond between the glans and chamber is rock solid as if being cemented in place. With such a connection there is no space for water nor expansion of air volume under traction.
Certainly not up to 15 lbs or so at which point less than perfect application of the Glans-Lock principal will be tested, and if not exactly right… separation of the glans may occur after this point.
Do report back on your experience. Btw, just make sure that you have a water separator in place to eliminate any chance of liquid entering into the vacuum pump, otherwise there will be problems.