I recently changed over to the front axle seals with a grease fitting to keep the seal packed and eliminate leaks.

Is there a similar product available for the rear? Can the tubes be drilled and tapped for a zerk fitting just inside the standard seal?

 

The seals you show keep debris out of the front axle tubes. There is no need for that with the rear axle as the seals are on the outboard ends of the tubes.
If you are looking to make the rear axle bearings grease-able, I don't see a need for that. The bearings and seals are lubricated with oil from the differential.
That seems to work well. I have 253,000 miles on my original axle seals and bearings. (Front and rear)

 

If you think those seals are doing diddly squat, think again. Also, if you DO have an inner seal leak, it's best to know so you can address it. Those things you have pictures are only going to mask the issue. IMO, it's always better to know you have a problem as soon as possible. Issues don't tend to remedy themselves when ignored.

...and as ronjenx highlights, no need for anything in the rear either. A leaking seal will need to be replaced from time to time.....that is just part of a solid axle vehicle.

 

are you running a JK with a rear steer set up?

 

And with those TF seals you cannot or it is difficult to use the factory white splined spacer washer on the axle to reinstall unless you put the axle in a bit with the plastic spacer and seal on the axle and then install the TF seal behind it after the axle is half in. That plastic washer lifts the spline of the axle off the bottom of the tube and keeps it clean while pushing in and keeps the crap out of the inner seal. The TF seals won't stop muddy water from going in but they will stop it from getting out due to the ridge on the seal body. I just run clean water in there from time to time to flush the tubes especially after going through mudholes.