By fixed...do you mean something like this??

Bartley Heath
bartley@DoubleDTrailers.com
Buy Factory Direct and $ave at DoubleDTrailers.com

Fixed or Solid rear tack:  I would rather have hands down.  No leaks (to speak of) no dust coming over the top or thru the gaps.

Folding rear tack: items can get wet, dusty, but can close to load 4 wheelers or whatever or some use them because they have not thought the horse to load and unload without having trouble.

The Sundowner we have now has a folding tack and I HATE IT, can not even leave the windows open when it rains because everything will get wet from blowing rain.  We do not leave the drop downs open just slide the window open for air to circulate (spell check).....  Working on turing it into a solid enclosed tack.

The colapable colapses? Pretty obvious that if you need the space to maybe haul something wide like a carriage you couldn't do it in the one that is fixed.

The bottom is the easy fix, what about the 4" to 6" gap on the top edge between the roof and tack wall?

What if you tried Baler Belt? I used the 4" on the bottom of my collapsable tack to keep shavings out, but it seems pretty stiff. You could use the 8" or 10" and just screw it to the top of the tack. That way it's easy to collapse the tack but the belt is stiff enough that it stays upright and keeps water and dirt out.

That might work too.

I have a sheet metal man working on using light gauge diamond tread alum. to completely seal everything off.  So far I am in it for the cost of the 4'x10' sheet for $120. bucks.  (but I use this to update older trailer running boards and splash guards also)  He wanted to use the alum. sheet so we would not have to use any paint or protection on it.  The gal. or sheet metal was alot cheaper but would have to prep and paint it or powder coat it.

Trade ya.  The people I got my trailer from took out and sold the rear tack/saddle rack and then decided they really did need it and built a fixed one and I don't like it.

If you are worried about pee getting into your tack area - just cut a piece of mat to fit in the area. 

The edge of the mat keeps the pee flowing on by the tack area and your stuff on the floor is elevated so it too never gets pee on the bottom. 

Also helps (doesn't completely) keep sawdust from getting in the tack area.

Collapsable Rear Tack for our outfit.... We haul saddles in the DR and Midtack.... Most of the time the rear tack is folded out of the way. Trailer has ramp over full cam lock doors with no center post.

I am wondering why you are concerned about sealing the top?

When selling trailers, or for resale, it seems like it's 50/50.

Collapsible rear tacks let you haul more than horses or make it easy to haul a young horse or problem horse without walking in the opening and being in the trailer ahead of them.  They do let junk under the wall, but that's fixable.

My personal choice is collapsible with cam locks and no center post.  I keep the tack wall back all of the time...I only have it to begin with for resale...collapsible is better than none at all...I always put my saddles in the front dressing room or mid tack.  I do buy problem horses and some young horses and I don't want to haul them home without being able to safely load them and have plenty of room to escape trouble....they all learn to load correctly once I get them home, but that one loading experience can be unnerving, so I play it safe.  Actually my trailer of choice is a Platinum C Sport with the one big slant divider in the middle and full rear door...that way I can haul the horses facing the rear of the trailer backwards.  I have never had any bad experiences with even the worst horses loading and hauling this way.