The tow vehicle is a Toyota 4Runner, implements to be determined but are a least a BX'ish tractor, mid-mower and a blade or blower for snow. Planning an FEL and later a tiller.
I towed a 5,000# boat with surge brakes behind my 4Runner. The truck actually handled it quite well, but the surge brakes were woefully inadequate. I had constant brake problems on the 4Runner as a result (warped front rotors and binding rear drums). Learned my lesson there and my next truck was an Expedition with tow package rated at 9,200# towing capacity.
Figure the tractor is 1,300# dry, 400# FEL, 300# MMM, and at least 500# for a tiller and you get up there in weight in a real hurry.
Some other things to consider:
What MMM are you looking at? a 54" cut deck has a solid 6" or more in 'excess' width for the deck itself...the 54" is just for the blade swath...you need to add the deck and discharge to the width. My 60" deck with bagger boot barely makes it onto my 8' deck with my stakesides installed.
The absolute bare minimum length I would consider is a 14' deck. My 20' dovetail has 18' of flat deck and my BX with FEL and Woods BH fills all but 2 feet of it. The tiller will take a good chunk of deck room...almost what my BH eats up.
It seems everyone on here hates single axle trailers??? I like how they are easy to handle and back in to tight spots.
I had a 3,500# 5' x 10' single axle trailer before I got my 10k# 20' dovetail dual axle. After I got my big trailer, I REALLY missed my smaller trailer for around the yard. But really, that's just one of the many things I do with my trailer and the other 95% of my tasks require a heavier trailer.
And yes, it seems we do all hate single axle trailers...especially for hauling equipment. I hauled my tractor on that single axle and I'm lucky I didn't have any real problems. Electric brakes are IMPERATIVE when towing these tractors...I remember once actually swerving under braking when my Expedition ran out of brakes stopping at a short light. Very unpleasent.
I vote 7' x 14' or 7' x 16' 7,000# capacity landscaping or car-hauler trailer.
Careful with the landscaping trailers as the sometimes only have brakes on one axle. One is better than none, but both is best.
And don't skimp on the controller. I run a Tekonsha P3 and love it. The Tekonsha Prodigy is the current gold standard in controllers.
And you'll probably have to run your own 7 pin connector on your 4Runner...I believe mine only had a 4 pin connector. Not a biggie, but be sure you have that straight before you go to pick up your trailer.
And I'd very strongly consider a Weight Distributing hitch. I run one on my Expedition and LOVE it. Makes a world of difference. And I remember the rear of my 1997 4Runner being a little "spongy"...you'd benefit greatly from a WD hitch.