Newbie questions - Building a (midsize) Tiny Tear

Long time reader and lurker - First time poster! I'm going to start a tear in the near future - 5' wide, 9' long, 4' high. Similar in profile to the 'Phil's Windsong' The interior will be very minimalist with the 'standard' galley in the rear
Will 1 1/2 by 3 inch box tubing with 4 crossmembers suffice for the frame? What gauge?
I'll need a 1500 torsion axle for a 60 inch platform, similar to the Reliable axle Notrhern sells for building a snowmobile trailer, but the only one they stock is a 45 degree down angle and I need a 10 degree up angle, coupled with a low profile mount (so I can keep the platform as close to the roadway as possible, especially since I'm using 15 inch wheels) - Reliable sells exactly such an axle, but Northern doesn't stock them . . . . what's a good source to order it 'custom built' from? We have a compact 5 door hatch (Mazda Protege 5) and I want to keep the trailer height at or below that of the car, which is about 55 inches. Can these axles be ordered with longer spindles so you can use FWD style car wheels? I would like to use the same wheels as my car uses if possible, so one spare can work for both
Most tears have the axles off-centered quite a bit to the back. I will have a small A/C and a Honda EU2000 genset and the spare tire in front near the tongue - Will the battery, fridge, water tank, galley and all weigh enough to keep me from having too much tongue weight? I'm shooting for about an 800 to 900 pound trailer. Would you wait until the project is finished and then position the axle last, so it can be adjusted for about 80 pounds of tongue weight? I like the look of the axle farther back, and as low to the ground as I want to make this one, it would sure help with not dragging the back end going in and out of gas stations and such
I have lots of experience building both trailers (though not camping trailers) plus projects made of plywood and epoxy . . . . I've built several small boats and dingys so I don't see any major hurdles to overcome. I have a welder and can use it plus most of the necessary tools. Need to get this finished by early fall so we can make a cross-country trip
Don
Will 1 1/2 by 3 inch box tubing with 4 crossmembers suffice for the frame? What gauge?
I'll need a 1500 torsion axle for a 60 inch platform, similar to the Reliable axle Notrhern sells for building a snowmobile trailer, but the only one they stock is a 45 degree down angle and I need a 10 degree up angle, coupled with a low profile mount (so I can keep the platform as close to the roadway as possible, especially since I'm using 15 inch wheels) - Reliable sells exactly such an axle, but Northern doesn't stock them . . . . what's a good source to order it 'custom built' from? We have a compact 5 door hatch (Mazda Protege 5) and I want to keep the trailer height at or below that of the car, which is about 55 inches. Can these axles be ordered with longer spindles so you can use FWD style car wheels? I would like to use the same wheels as my car uses if possible, so one spare can work for both
Most tears have the axles off-centered quite a bit to the back. I will have a small A/C and a Honda EU2000 genset and the spare tire in front near the tongue - Will the battery, fridge, water tank, galley and all weigh enough to keep me from having too much tongue weight? I'm shooting for about an 800 to 900 pound trailer. Would you wait until the project is finished and then position the axle last, so it can be adjusted for about 80 pounds of tongue weight? I like the look of the axle farther back, and as low to the ground as I want to make this one, it would sure help with not dragging the back end going in and out of gas stations and such
I have lots of experience building both trailers (though not camping trailers) plus projects made of plywood and epoxy . . . . I've built several small boats and dingys so I don't see any major hurdles to overcome. I have a welder and can use it plus most of the necessary tools. Need to get this finished by early fall so we can make a cross-country trip
Don