I'd screw a 2x10 to the bottom chord of the truss each side, about 12' long.
I'd procure some 2" square tubing, 1/4" wall, that's long enough to span from floor to the underside of the bottom chord. Could also be 2" Sch 40 black pipe.
I'd weld a "U" shaped cup to the top end of the tube, width to match the 3 thicknesses of 2x material created above.
When its time to use the hoist, get out the posts and use the stud on the leveling foot to just touch the U-cup to the bottom of the truss so the column won't fall over. Repeat left and right.
Now use your hoist with confidence. Put the tubular columns away when finished.
I did something similar to this.
First, I sandwiched an 8-foot 2x6 betweeen two 8-foot 2x10s with the gap at the top. I slipped it over the bottom of a truss FOR LATERAL SUPPORT ONLY and attached with 3" screws from both sides.
I made 8-foot long end braces to spread the lateral forces across several trusses. The braces were made by ripping a sheet of 3/4" plywood into four 12"x94-1/2" pieces. Two pieces had 1-1/2" x 5" slots cut 22-1/2" apart to slide over the bottom chords of the trusses. The other two were cut the same except the center slot was 4-1/2" wide and 10-1/2" deep to slide over the bottom of the beam. These dimensions allowed the braces to extend 1-1/2" above the bottom chords of the trusses, and 1-1/2" below the bottom of the beam. Two plywood braces were set in place and attached to the ends of the beam with 3" screws. After cutting 1/2" x 3-1/2" notches out of both ends of the 2x10s, 8-foot 2x4s were laid flat on top of the truss chords and screwed to the inboard (beam) sides of the plywood braces. 9" long blocks of 2x4 were laid against both sides of all the trusses and screwed to the top 2x4s and the plywood braces. Two more 8-foot 2x4s were screwed to the bottoms of the 9" blocks and along the bottom edges of the braces. Finally, the other two braces, with the wide middle slots, were slipped into place below the bream and screwed to the top and bottom 2x4s and all of the 9" blocks. THIS WAS ALL DONE TO PREVENT ANY TWISTING OF THE TRUSSES WHEN THE BEAM WAS CARRYING A LOAD - NOT TO SUPPORT THE LOAD! This was probably overkill, but dimensional lumber and plywood is a lot cheaper than a broken truss.
The weight was carried by basement jack posts at each end of the beam. I attached 4-foot long 2x6s to the tops of the posts. These were aligned with the braces when in use to provide a friction fit at the top. At the bottom, the posts were supported by triple 4-foot long 2x8's. The top 2x8s had holes drilled through them to accept the bottom on the post. This kept the bottom of the post in place, with the whole base providing a friction fit to the floor.
The only thing I might do different might be sandwiching 9-1/2 inch x 8-foot pieces of 3/4" plywood between the 2x6 and the 2x10s with through-bolts for a little extra insurance against deflection in the beam, although I used this setup to pull engines and handle awkward body components such as hoods and roofs, as well as moving other heavy items in and out of my pickup bed for years with no problems ever.
