Teardrops n Tiny Travel Trailers

Been lurking for a while with a few posts here and there.
I did this design in Fusion 360 which is great fun but has a bit of a learning curve adn there are parts of it I haven't quite figured out...like how to make the hatch open and how to align spars etc...
Build will be a Foamie hybrid. Love the woodie look so will be using okume for my outerskins.

Inner skins will be either pmf or birch
headliner will be pmf
Doors will be wood sandwich like the skin (color in the pictures for contrast.
Planning for fantastic fan, working porthole windows (tab portholes if I can find them)
All 12V no shore power. portable Solar panels. I've found that parking where solar is best isn't actually where you want to situate your rig. Battery large enough to handle charging the laptop and phones, running the fan, led lights. I'm a western person and will be doing most of my camping in areas that don't need AC. In cooler weather I have great sleeping bags
Galley will have my propane cook stove and small tank, cooler, and 5 gallon aquatainer, prep area, and maybe a sink cutout covered by a cutting board. I prefer cooking at a site's picnic table if the weather is agreeable.
Operable front window or fixed stargazer. Either built like Jeff and Zaretas (viewtopic.php?f=50&t=68013&hilit=jeff) or perhpaps a purchased dual pane RV window 20x42 https://www.rvwindows.com/products/rv-e ... ries-1800/ (~400 less for single)
Also considering a box under the floor, futon type seat etc...
Weight goal <800 lbs $ goal $2500-3000

So here are my questions
1. Do I really need spars or really just at the hatch, fan and as bracing for the stargazer window? If I eliminate the spars.
2. For the window I'm drawn to the idea of an RV window, and would actually cut it into the foam so that it sits flat (and size it a big as possible to allow that) and/or reform the profile to accommodate or if Lexan would do it as Jeff did in his build with perhaps some what of a cut in. Am I thinking about this right? Other options I should consider.

Plan is to order the trailer soon, and begin building sometime in May with a goal of being camping in it by fall.

Yea, you need the spars, it ties everything together and gives it strength. But what is your plan to attach the spars to the side walls?

I didn't see the size of the foam body, is it 4x8?

It looks like you are headed in the right direction...

Mike...

Thanks Mike
It's a 5x8 Ironton trailer, 5x9.5 trailer.

Spars-- My thought was that I'd set the spars into the 2 inch foam side walls--glued with TB2/GG/GS. Seems like Glen and some others had very few if any spars, others like KC quite a bit. I'm thinking I at least need them at the galley/rear bulkhead, fan, and around the window. Is there a spacing convention for them in foam 16oc?
If there is only plywood (1/8) on the skin I and the interior is pmf as would be the roof was thinking I might not need many.