Both axles on my plant trailer are braked
If you buy an old trailer that you know you can still get parts for...
I bought an OLD Ifor williams 3.5t 12ft flatbed, mechanically sound, and put a new set of brakes on it and fettled the lights. Whole trailer stands me in around £1200, and it tows superbly.
I friend of mine has a boat trailer and he reckons many people leave the brakes off the rear axle because those are the ones that get the most water when launching. I pointed him in the direction of the DVSA webpage that states if a trailer requires brakes then all wheels should have working brakes.