Thank you, Raspy, for your helpful response and assessment of the options! I also heard from Brian B-P, whom I contacted for his input as well since he had installed shocks on his Boler
with good results. I had been leaning toward shocks but several trailer service centers were trying to sell me on the equalizers (they also incorrectly assumed that my Bigfoot's equalizers had nylon bushings when they are all metal and both the spring leafs and equalizers seem in good shape).
I feel reassured that adding the shocks is the best way to go - once I can figure out what size axles I have! I had the drop axles replaced with straight axles when I first bought my Bigfoot
and nothing on the work receipt indicates the brand or size of axles. I will crawl under there tomorrow to see if I can find any imprints or labels, but I was just under there a month or so ago when sanding, priming and painting
the frame and I don't remember seeing anything labeling the axles. I measured an axle with a seamstress' tape measure today and got exactly 7" circumference; my auto mechanic used a caliper and got 2.5" diameter. I thought axles only come in 2.375" diam., 3" diam. and 3.5" diam, so not sure what to make of my or my mechanic's measurements.
I spoke with at least 24 different trailer parts stores and none of them have individual brackets to create one's own retro shock kit. I did learn that the weld-on Dexter shock kit is only hydraulic, not gas, so that's out. The bolt-on Lippert gas kit is very poorly-rated. So that leaves two potential gas shock retrofit kits that are pricey, but include everything needed and are available for 2.375" diam., 3" diam. and 3.5" diam. axles:
The Roadmaster Comfort Ride: Roadmaster Inc. - Tow Bars, Braking Systems & RV Accessories
The JoyRider Shock Kit: Joy Rider
The JoyRider is owned by a guy named Sonny, who lives here in Arizona. Sonny says that his JoyRider system helps dampen bounce and side-to-side movement because the shocks are installed at a 15 degree angle vertically as well as horizontally from the axle to the frame. Sonny said he would help guide my auto mechanic on the install to make it as easy. My mechanic is very honest, reliable and experienced with all sorts of autos, but has not installed shocks on a travel trailer before - he is willing to do it because he loves a challenge and he knows I have not had good luck with the high-priced RV mechanics I've tried so far.
I do not have the engineering background to determine if what Sonny says about his system has any credibility. Both systems are expensive, but I plan to use my Bigfoot
a lot over the next 20+ years and want to travel as far as Canada, so a smoother ride is important to me. Any input about these systems from those of you with enough engineering/suspension knowledge to be able to assess them is much appreciated.