Your Boler looks fantastic! CONGRATULATIONS! I have a 17' 1980 Boler as well and want to replace and recover my cushions .
I went to a foam/fabric store in Bradford, Ontario and purchased a twin mattress size piece of foam,
5 inches thick, high density. I had brought my old pieces with me and asked the owner to outline the old foam against the new foam.
That piece of foam with tax was approx. $300 but so comfy Steve wouldn't let me go any further with it. Once we "moore" our trailer the bed at the back remains a bed. We initially cover it with a packing blanket from Princess Auto and then make the bed from there.
The place I bought the foam from has been in business for two generations and I was delighted to find fabric from the late 70's that suited my needs. I bought 10 metres. I really have no idea how much I need.
In hindsight I am kicking my butt for not saving the original covers with working zipper. It would have been so easy to take out the stitches and use the pieces as a template, allowing for the extra foam height.
Last year I bought a single foam mattress from Leon's on special for $99. Very comfy, 5" thick.
This time I am going to trace and cut it myself, using the old foam as my pattern, bring out the electric cutting knife, upholstery spray glue, batting
and get to work.
I am going to use the original covers as the pattern and the original zippers. The post office sells wide rolls of brown craft paper that I have to outline the pattern. I'm not going vinyl on the bottom, instead using some raw but washed canvas. I cheaper out here as well and got the biggest
canvas painters cloth on sale a either Canadian Tire or Home Hardware. I had to cut it in half to pre wash it in an oversized washing machine at the laundromat.
I think I had better make one seat cover out of broadcloth just to get the feel of it before I cut into my precious vintage fabric.
The best of luck with your project.
I am very curious. What was the asking price of the trailer? What year is it?
Just for your own piece of mind get a safety check done on it, especially the bearings and brakes
Cheers from Alliston Ontario and have a fantastic summer in your Boler. I love mine!
P.S. Every year one or two people come knocking on my door asking if mine is for sale
. It's not. Just warning you in advance. I don't give them a tour politely telling them I have misplaced the key....