For the HFBR check this old video where the exercise is demonstrated on a regular old bench. You can do them like this and they are pretty brutal. IF the gym has any form of turf or implement that can be pushed just push that. If not surely it has dumbbells and you could do farmers walks in a strip at that facility with reasonable weights. Not totally the same exercise but it will give you a good stimulus.
Sometimes we have to get creative with this stuff. We try to write the programs to be reasonably accessible at most facilities but not all places have some form of GHR or turf quite yet, give it a few more years.