For any price point the requirement it be "lightweight" is going to conflict with "thorn- and tear-proof". You could spend a lot of money and get some spectra sailcloth that you could lift a tank with. Pinholes would be filed every year or two with seam sealer. But make sure you're sitting down when you look at the price. Lightweight Dacron sailcloth is a lot cheaper and might withstand UV longer.

Cheap tarps have advantages of their own. They are inexpensive enough that you can buy them in bulk and afford to replace them frequently enough to avoid the down side of their weaknesses. As they are replaced the worn ones can be used as ground clothes and used that are less demanding. This is a difference in degree not kind. Even the most expensive tarp, made of unobtainium and the souls of orphans, assembled by virgins using occult rites and cyclotrons, wear out eventually.

Camouflage is also problematic. First, because there is no universal pattern or color and second; because there is nothing that will get people to hike over to something and explore like an even marginally ineffective camouflage job. The act of concealment makes people wonder what your covering up. It also implies you're up to no good.

A neutral subdued color is often as effective as an actual camouflage pattern and it sends the message that your seeking to avoid visual pollution, not sneaking around.

The easiest specification is the "numerous reinforced grommets and tie straps / loops" these are pretty easy to make or install yourself. If you don't have the experience put it on your list of skills to learn. The US Army manual for canvas repair and Sailmaker's Apprentice are good sources.

Alternatively you can take it to a sailmaker's or cobbler shop. Some tailors or seamstresses might be sympathetic but their materials are usually much finer and they may damage their machines if they try to use them. Typically they just break needles but a stripped gear isn't impossible.