Perhaps add a helper field to your template part that sets all the fields you need. Then your form load rule would only have to set the helper field! So - you could have a Boolean in your template part data source (not on the form) called "set" or whatever, and then in your form load rules, set that field to "true" - the template part field would have the rules you needed. When they run, set the field back to false so it is ready to go again. Make sure the rules to set values only run when set = true.