To be honest I have no idea if they will. I will of course leave a layer of air in the bridge in case they pause midway. I may eventually turn this into an ADF and guppy set up if I do the bridge but the guppies are a secondary addition. Right now I am still debating the two 10s with bridge vs the 20 long with out a bridge.
If my mother in law calls me later and says she can bring up the 20 long, then problem solved. I would prefer to give them the floor space then something visually appealing to me but might be useless/confusing for the frogs.