Update, after reviewing the above, and taking your helpful suggestions:
Well, I have taken the GMRS dual band rated N9TAX slim jim out of the upstairs window (thanks for reminding me of the metal box of aluminum siding issue...I had had to wire an ethernet cable out to a Wifi repeater last year to get signal and photos back from outside battery operated wifi security cameras...same issue, DUH), and now it is strung up by zip ties on a long bamboo pole which is atop about 10 feet of 1/2" galvanized pipe stuck in the ground about 2 feet from the garage, and likely the top at about 16-18 feet estimated. The antenna only makes contact with the bamboo, and the galvanized starts about a foot or so below the bamboo. Using the same RG-8X cable and again my HT 5 watt, which altogether is measuring at 1.8 SWR.
I am getting on one local repeater (Channel 30 at 462.725) about a 200 cycles per minute static, which I can squelch out, but is still there, and the repeater is in the direction of the garage shingled roof, which I am not yet above the peak of. In messing around and repositioning the antenna, I think I am getting clearer signal sometimes, but am wondering whether the zip ties I used to attach the slim jim twin lead could be the problem. To get it up more quickly for testing purposes, I zipped alternating sides of the wire leads to the bamboo at about 4 locations, whereas N9TAX seems to recommend punching holes in the plastic ladder rungs and zipping away from the wire leads and just on the rungs. Do you think that makes a difference?
I went ahead and ordered the 25 watt Radioddity DB25-G today, and considered ordering LMR or KMR 400 cable, but at this point, I will be repositioning antenna, adding the 25 watt as a base station, and seeing what happens. Will likely keep you posted, and thanks for the wonderful advice, and yes, the video, which I had seen before, was a great review and reminder, Thanks Steve!!