CSG,
I recently went through something similar. I have a TV Oracle, the predecessor to the 85. It is a 3 inch F7.4 triplet with 2" diagonal, so kind of in between the 76 and 85. I used a TV 8-24 Zoom and Williams Optics 45 deg erecting prism for birding. I had it mounted on an Alt/Az head intended for astronomy and a Bogen (Manfrotto) studio tripod. The issue for me was weight and transportability (see disclaimer below) and only secondarily weather proofing.
The telescope with diagonal and eyepiece is probably in the 9 lb range, and finding a portable photo tripod/head to handle that steadily is tough. My astronomy setup up with head and tripod worked beautifully, but it weighed around 20 lb. That's OK at home looking off the balcony, or to unload from the car, but not to carry around in the field. Also, assembly and disassembly was not instantaneous. The field of view of the TV Zoom is not very wide, and the lowest power was around 23x if I remember right, but of course the views were very good.
I opted for an Opticron MM3 60 spotting scope. It weighs just over two lb with zoom eyepiece, and it works nicely on a portable tripod with either ball head or alt/az head. It is very backpack transportable, quickly assembled, and in the field it's easy to carry scope/tripod combination over the shoulder. The think it may weight 6 lb assembled. The view is excellent, and I prefer the lower lowest power (15x) which gives a wider actual field. The Oracle was better at the higher power, but the color in the Opticron seemed a bit more vibrant and the Opticron was easier to use in a number of respects. I went with a 60mm spotter because I wanted portability (size and weight) and I had seen good reviews of both the 50mm and 60mm Opticron.
So if you are staying in one spot, stick with what you have, but if you plan to wander around with your telescope, consider investing in a compact spotter and decent portable tripod/head combo.
Disclaimer: I have only had my spotter out in the field five or six times in the past four months although I bird a couple times a week. I try to go out with experienced birding groups whenever possible, and more often than not there are a couple people who bring spotting scopes. So in some ways a spotting scope is like a large telescope or a boat, it may be better to have a friend with a good spotting scope than to buy one. OTH, my Oracle is packed up and back to strictly astronomy duty and I use the Opticron almost daily from home to look at sea birds out my window.
Alan