ZTR's can be a PIA to get onto trailers because they are a lot lower than a tractor style mower
My trailer is mesh floored, it was custom made for a 2000 series Cub
It is over 20 years old and the floor is perfect , including having the mesh welded in the right way to stop stuff sliding forward .
It was used for the Cub then modified slightly to take a Great Dane Chariot & I got it as a contra deal with a commercial customer when he got his new trailers made to take the Walkers and a lock up at the front for hand helds and push mowers that get "borrowed" by passers by when he is out of sight .
If you are going to use the tailgate as a ramp you will have to get a third hinge welded on if you want it to last more than 1 year
Off the shelf trailers usually create more problems than they are worth as they are built to be as light as possible ( which is why the floors bend )
I can not count the number of times I have been asked to repair one for my commercial customers , they are just not made to be used every day.
As for finish forget any type of paint pay the extra for Galvanizing
Having mowers driven in and out 20 times a day will scratch through the paint , water will get under it and start rusting
Also have a close look at the tailgate floor joint
If the hinge end of the tailgate sits higher than the floor then the deck will catch on it when driving off damaging both the deck & the tailgate .
IF a tiny market in the white pimple on the brown bum of the planet can have 12 different manufacturers of custom built mowing contractors trailers then surely the bastion of the free market would have over 1000 .
You have to treat trailers as what they are, a TOOL that you use to earn a living with .
You would not last long trying to use Walmart mowers to do your mowing so why use a Walmart trailer.
IT is going to MAKE you money so the more you pay for it the better and remember it is a tax deduction and for a business it should be sales tax free ( or at least reduced rate) so go for quality , durability & ease of use, even if that means taking your old trailer to the shop / factory complete wih mowers & gear then hooking up the new one and doing a "test load "
If the shop will not allow this then that speaks volumes for the quality of what they are trying to sell you .