Great info guys, definitely a lot of inspiration here and it gives me a lot more confidence in what I want to do. I REALLY don't want to get rid of my M416 but it's not going to be big enough to do a "sleep-in" build for 3ppl and a dog. Wife insists on not climbing a ladder and wants something insulated to camp year round comfortably (she says she's not getting any younger). NOW the tells me. So I need to abandon my M416 build and I'll have to sell it to fund the start of an enclosed trailer.
So after the ~$2k for the base trailer, how much am I looking at to get good suspension (springs and shocks or torsion) and beefing up the main frame to accept "lock n roll" and fell comfortable enough that it'll hold up to the rigors of off-road use? I don't know how to weld so this is my biggest concern. Once I'm beyond that I am very comfortable with my carpentry skills to take it from there and have welders add extra bits and pieces as I go.
Exactly why we're going this route. Realistically, depending on what "extras" you want outside of a comfortable, insulated sleeping space, galley, decent suspension and a LNR or similar coupler (no electric, water, or anything) you're going to be around $3,500-$5,000. Lower end if you plan well, design simple and save some cost on materials/features. Higher end, or more, if you buy a new trailer as a starting point, make mistakes, want everything new, want some more luxurious features and have someone do some welding, etc.
We are PLANING to come in under $6,500 and have everything we want. Windows, roof vent, 12 V DC throughout cabin, batteries, reinforced frame, extended tongue, some storage solutions, leveling jacks, spare water/fuel, propane, etc.
If you could see what is hidden out of sight on cheap enclosed trailers you would puke. Do a lot of research on brands and models within the brand before buying.
Truth. In my previously linked build thread, I covered some of the cheap ways they make a 5x8 a $2,000 trailer instead of $3,500 trailers. Curved two piece roofs, multiple piece sides, some poor welds, piss poor wiring (both wire quality and installation practices/techniques), poor finish on sealants, etc.
That said, the cheap trailer was still the right call for us. Some things it saved us was money spent on things we didn't need. We didn't need upgraded 15" wheels (changed them anyways), we didn't need all their silly small vents (we're adding our own that work better for a camper, not a cargo trailer, instead), we didn't need higher quality suspension (changing it anyway) and we didn't mind the poor wiring and less idea metal choices (Z vertical wall supports vs square tubing, as an example) as it's something we'll modify greatly anyway.
One thing I looked for was a boxed main frame and a good Dexter axle, which the Patriot 5x8 had. So of the $1,500 saved, $40 will go to rewiring it (which we'd do anyway to fit out new design needs) and about $300 to beef up the frame (which we would do anyways due to off road needs). So we still saved over a grand. We don't see the issue with the multi-piece sides or curved, two piece, roof. We'll keep the $1,000 and address those as maintenance items. If we were building a $20,000 fully decked out custom job, it might be of more concern for longevity, but as a budget friendly sleeping quarters to camp in, that'll still serve it's use for many, many trouble free years... the extra cost wasn't justified in our case.
Adjust your approach according to your needs, skill levels and budget.